5.135. kernel

Updated kernel packages that fix three security issues and several bugs are now available for Red Hat Enterprise Linux 6.3 Extended Update Support.
The Red Hat Security Response Team has rated this update as having important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2012-4508, Important
A race condition was found in the way asynchronous I/O and fallocate() interacted when using the ext4 file system. A local, unprivileged user could use this flaw to expose random data from an extent whose data blocks have not yet been written, and thus contain data from a deleted file.
CVE-2013-4299, Moderate
An information leak flaw was found in the way the Linux kernel's device mapper subsystem, under certain conditions, interpreted data written to snapshot block devices. An attacker could use this flaw to read data from disk blocks in free space, which are normally inaccessible.
CVE-2013-2851, Low
A format string flaw was found in the Linux kernel's block layer. A privileged, local user could potentially use this flaw to escalate their privileges to kernel level (ring0).
Red Hat would like to thank Theodore Ts'o for reporting CVE-2012-4508, Fujitsu for reporting CVE-2013-4299, and Kees Cook for reporting CVE-2013-2851. Upstream acknowledges Dmitry Monakhov as the original reporter of CVE-2012-4508.

Bug Fixes

BZ#1016105
The crypto_larval_lookup() function could return a larval, an in-between state when a cryptographic algorithm is being registered, even if it did not create one. This could cause a larval to be terminated twice, and result in a kernel panic. This occurred for example when the NFS service was running in FIPS mode, and attempted to use the MD5 hashing algorithm even though FIPS mode has this algorithm blacklisted. A condition has been added to the crypto_larval_lookup() function to check whether a larval was created before returning it.
BZ#1017505, BZ#1017506
A previous change in the port auto-selection code allowed sharing of ports with no conflicts, extending its usage. Consequently, when binding a socket with the SO_REUSEADDR socket option enabled, the bind(2) function could allocate an ephemeral port that was already used. A subsequent connection attempt failed in such a case with the EADDRNOTAVAIL error code. This update applies a patch that modifies the port auto-selection code so that bind(2) now selects a non-conflict port even with the SO_REUSEADDR option enabled.
BZ#1017903
When the Audit subsystem was under heavy load, it could loop infinitely in the audit_log_start() function instead of failing over to the error recovery code. This could cause soft lockups in the kernel. With this update, the timeout condition in the audit_log_start() function has been modified to properly fail over when necessary.
BZ#1020527
Previously, power-limit notification interrupts were enabled by default on the system. This could lead to degradation of system performance or even render the system unusable on certain platforms, such as Dell PowerEdge servers. A patch has been applied to disable power-limit notification interrupts by default and a new kernel command line parameter "int_pln_enable" has been added to allow users observing these events using the existing system counters. Power-limit notification messages are also no longer displayed on the console. The affected platforms no longer suffer from degraded system performance due to this problem.
BZ#1023349
Previously, when the user added an IPv6 route for local delivery, the route did not work and packets could not be sent. A patch has been applied to limit the neighbor entry creation only for input flow, thus fixing this bug. As a result, IPv6 routes for local delivery now work as expected.
BZ#1028592
A bug in the kernel's file system code allowed the d_splice_alias() function to create a new dentry for a directory with an already-existing non-DISCONNECTED dentry. As a consequence, a thread accessing the directory could attempt to take the i_mutex on that directory twice, resulting in a deadlock situation. To resolve this problem, d_splice_alias() has been modified so that in the problematic cases, it reuses an existing dentry instead of creating a new dentry.
BZ#1029423
The kernel's thread helper previously used larvals of the request threads without holding a reference count. This could result in a NULL pointer dereference and subsequent kernel panic if the helper thread completed after the larval had been destroyed upon the request thread exiting. With this update, the helper thread holds a reference count on the request threads larvals so that a NULL pointer dereference is now avoided.
BZ#1029901
Due to a bug in the SELinux Makefile, a kernel compilation could fail when the "-j" option was specified to perform the compilation with multiple parallel jobs. This happened because SELinux expected the existence of an automatically generated file, "flask.h", prior to the compiling of some dependent files. The Makefile has been corrected and the "flask.h" dependency now applies to all objects from the "selinux-y" list. The parallel compilation of the kernel now succeeds as expected.
All kernel users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.
Updated kernel packages that fix several bugs are now available for Red Hat Enterprise Linux 6 Extended Update Support.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Bug Fixes

BZ#969341
When adding a virtual PCI device, such as virtio disk, virtio net, e1000 or rtl8139, to a KVM guest, the kacpid thread reprograms the hot plug parameters of all devices on the PCI bus to which the new device is being added. When reprogramming the hot plug parameters of a VGA or QXL graphics device, the graphics device emulation requests flushing of the guest's shadow page tables. Previously, if the guest had a huge and complex set of shadow page tables, the flushing operation took a significant amount of time and the guest could appear to be unresponsive for several minutes. This resulted in exceeding the threshold of the "soft lockup" watchdog and the "BUG: soft lockup" events were logged by both, the guest and host kernel. This update applies a series of patches that deal with this problem. The KVM's Memory Management Unit (MMU) now avoids creating multiple page table roots in connection with processors that support Extended Page Tables (EPT). This prevents the guest's shadow page tables from becoming too complex on machines with EPT support. MMU now also flushes only large memory mappings, which alleviates the situation on machines where the processor does not support EPT. Additionally, a free memory accounting race that could prevent KVM MMU from freeing memory pages has been fixed.
BZ#972599
When the Active Item List (AIL) becomes empty, the xfsaild daemon is moved to a task sleep state that depends on the timeout value returned by the xfsaild_push() function. The latest changes modified xfsaild_push() to return a 10-ms value when the AIL is empty, which sets xfsaild into the uninterruptible sleep state (D state) and artificially increased system load average. This update applies a patch that fixes this problem by setting the timeout value to the allowed maximum, 50 ms. This moves xfsaild to the interruptible sleep state (S state), avoiding the impact on load average.
BZ#975577
A previously-applied patch introduced a bug in the ipoib_cm_destroy_tx() function, which allowed a CM object to be moved between lists without any supported locking. Under a heavy system load, this could cause the system to crash. With this update, proper locking of the CM objects has been re-introduced to fix the race condition, and the system no longer crashes under a heavy load.
BZ#976695
* The schedule_ipi() function is called in the hardware interrupt context and it raises the SCHED_SOFTIRQ software interrupts to perform system load balancing. Software interrupts in Linux are either performed on return from a hardware interrupt or are handled by the ksoftirqd daemon if the interrupts cannot be processed normally. Previously, the context of the schedule_ipi() function was not marked as a hardware interrupt so while performing schedule_ipi(), the ksoftirqd daemon could have been triggered. When triggered, the daemon attempted to balance the system load. However at that time, the load balancing had already been performed by the SCHED_SOFTIRQ software interrupt so the ksoftirqd daemon attempted to balance the already-balanced system, which led to excessive consumption of CPU time. The problem has been resolved by adding irq_enter() and irq_exit() function calls to schedule IPI handlers, which assures that context of softirq_ipi() is correctly marked as a hardware interrupt and the ksoftirqd daemon is no longer triggered when the SCHED_SOFTIRQ interrupt has been raised.
BZ#977667
A race condition between the read_swap_cache_async() and get_swap_page() functions in the Memory management (mm) code could lead to a deadlock situation. The deadlock could occur only on systems that deployed swap partitions on devices supporting block DISCARD and TRIM operations if kernel preemption was disabled (the !CONFIG_PREEMPT parameter). If the read_swap_cache_async() function was given a SWAP_HAS_CACHE entry that did not have a page in the swap cache yet, a DISCARD operation was performed in the scan_swap_map() function. Consequently, completion of an I/O operation was scheduled on the same CPU's working queue the read_swap_cache_async() was running on. This caused the thread in read_swap_cache_async() to loop indefinitely around its "-EEXIST" case, rendering the system unresponsive. The problem has been fixed by adding an explicit cond_resched() call to read_swap_cache_async(), which allows other tasks to run on the affected CPU, and thus avoiding the deadlock.
Users should upgrade to these updated packages, which contain backported patches to correct these bugs. The system must be rebooted for this update to take effect.
Updated kernel packages that fix several security issues and bugs are now available for Red Hat Enterprise Linux 6 Extended Update Support.
The Red Hat Security Response Team has rated this update as having important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2013-0311, Important
A flaw was found in the way the vhost kernel module handled descriptors that spanned multiple regions. A privileged guest user in a KVM (Kernel-based Virtual Machine) guest could use this flaw to crash the host or, potentially, escalate their privileges on the host.
CVE-2013-1773, Important
A buffer overflow flaw was found in the way UTF-8 characters were converted to UTF-16 in the utf8s_to_utf16s() function of the Linux kernel's FAT file system implementation. A local user able to mount a FAT file system with the "utf8=1" option could use this flaw to crash the system or, potentially, to escalate their privileges.
CVE-2013-1796, Important
A flaw was found in the way KVM handled guest time updates when the buffer the guest registered by writing to the MSR_KVM_SYSTEM_TIME machine state register (MSR) crossed a page boundary. A privileged guest user could use this flaw to crash the host or, potentially, escalate their privileges, allowing them to execute arbitrary code at the host kernel level.
CVE-2013-1797, Important
A potential use-after-free flaw was found in the way KVM handled guest time updates when the GPA (guest physical address) the guest registered by writing to the MSR_KVM_SYSTEM_TIME machine state register (MSR) fell into a movable or removable memory region of the hosting user-space process (by default, QEMU-KVM) on the host. If that memory region is deregistered from KVM using KVM_SET_USER_MEMORY_REGION and the allocated virtual memory reused, a privileged guest user could potentially use this flaw to escalate their privileges on the host.
CVE-2013-1798, Important
A flaw was found in the way KVM emulated IOAPIC (I/O Advanced Programmable Interrupt Controller). A missing validation check in the ioapic_read_indirect() function could allow a privileged guest user to crash the host, or read a substantial portion of host kernel memory.
CVE-2012-4542, Moderate
It was found that the default SCSI command filter does not accommodate commands that overlap across device classes. A privileged guest user could potentially use this flaw to write arbitrary data to a LUN that is passed-through as read-only.
CVE-2013-1767, Low
A use-after-free flaw was found in the tmpfs implementation. A local user able to mount and unmount a tmpfs file system could use this flaw to cause a denial of service or, potentially, escalate their privileges.
CVE-2013-1848, Low
A format string flaw was found in the ext3_msg() function in the Linux kernel's ext3 file system implementation. A local user who is able to mount an ext3 file system could use this flaw to cause a denial of service or, potentially, escalate their privileges.
Red Hat would like to thank Andrew Honig of Google for reporting the CVE-2013-1796, CVE-2013-1797, and CVE-2013-1798 issues. The CVE-2012-4542 issue was discovered by Paolo Bonzini of Red Hat.

Bug Fixes

BZ#952612
When pNFS (parallel NFS) code was in use, a file locking process could enter a deadlock while trying to recover form a server reboot. This update introduces a new locking mechanism that avoids the deadlock situation in this scenario.
BZ#955503
The be2iscsi driver previously leaked memory in the driver's control path when mapping tasks.This update fixes the memory leak by freeing all resources related to a task when the task was completed. Also, the driver did not release a task after responding to the received NOP-IN acknowledgment with a valid Target Transfer Tag (TTT). Consequently, the driver run out of tasks available for the session and no more iscsi commands could be issued. A patch has been applied to fix this problem by releasing the task.
BZ#956295
The virtual file system (VFS) code had a race condition between the unlink and link system calls that allowed creating hard links to deleted (unlinked) files. This could, under certain circumstances, cause inode corruption that eventually resulted in a file system shutdown. The problem was observed in Red Hat Storage during rsync operations on replicated Gluster volumes that resulted in an XFS shutdown. A testing condition has been added to the VFS code, preventing hard links to deleted files from being created.
BZ#956933
A bug in the lpfc driver allowed re-enabling of an interrupt from the interrupt context so the interrupt handler was able to re-enter the interrupt context. The interrupt context re-entrance problem led to kernel stack corruption which consequently resulted in a kernel panic. This update provides a patch addressing the re-entrance problem so the kernel stack corruption and the subsequent kernel panic can no longer occur under these circumstances.
BZ#960410
Previously, when open(2) system calls were processed, the GETATTR routine did not check to see if valid attributes were also returned. As a result, the open() call succeeded with invalid attributes instead of failing in such a case. This update adds the missing check, and the open() call succeeds only when valid attributes are returned.
BZ#960416
Previously, an NFS RPC task could enter a deadlock and become unresponsive if it was waiting for an NFSv4 state serialization lock to become available and the session slot was held by the NFSv4 server. This update fixes this problem along with the possible race condition in the pNFS return-on-close code. The NFSv4 client has also been modified to not accepting delegated OPEN operations if a delegation recall is in effect. The client now also reports NFSv4 servers that try to return a delegation when the client is using the CLAIM_DELEGATE_CUR open mode.
BZ#960419
Previously, the fsync(2) system call incorrectly returned the EIO (Input/Output) error instead of the ENOSPC (No space left on device) error. This was caused by incorrect error handling in the page cache. This problem has been fixed and the correct error value is now returned.
BZ#960424
In the RPC code, when a network socket backed up due to high network traffic, a timer was set causing a retransmission, which in turn could cause even larger amount of network traffic to be generated. To prevent this problem, the RPC code now waits for the socket to empty instead of setting the timer.
BZ#962367
A rare race condition between the "devloss" timeout and discovery state machine could trigger a bug in the lpfc driver that nested two levels of spin locks in reverse order. The reverse order of spin locks led to a deadlock situation and the system became unresponsive. With this update, a patch addressing the deadlock problem has been applied and the system no longer hangs in this situation.
BZ#964960
When attempting to deploy a virtual machine on a hypervisor with multiple NICs and macvtap devices, a kernel panic could occur. This happened because the macvtap driver did not gracefully handle a situation when the macvlan_port.vlans list was empty and returned a NULL pointer. This update applies a series of patches which fix this problem using a read-copy-update (RCU) mechanism and by preventing the driver from returning a NULL pointer if the list is empty. The kernel no longer panics in this scenario.
Users should upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.
Updated kernel packages that fix several bugs are now available for Red Hat Enterprise Linux 6 Extended Update Support.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Bug Fixes

BZ#911266
The Intel 5520 and 5500 chipsets do not properly handle remapping of MSI and MSI-X interrupts. If the interrupt remapping feature is enabled on the system with such a chipset, various problems and service disruption could occur (for example, a NIC could stop receiving frames), and the "kernel: do_IRQ: 7.71 No irq handler for vector (irq -1)" error message appears in the system logs. As a workaround to this problem, it has been recommended to disable the interrupt remapping feature in the BIOS on such systems, and many vendors have updated their BIOS to disable interrupt remapping by default. However, the problem is still being reported by users without proper BIOS level with this feature properly turned off. Therefore, this update modifies the kernel to check if the interrupt remapping feature is enabled on these systems and to provide users with a warning message advising them to turn off the feature and update the BIOS.
BZ#920264
The NFS code implements the "silly rename" operation to handle an open file that is held by a process while another process attempts to remove it. The "silly rename" operation works according to the "delete on last close" semantics so the inode of the file is not released until the last process that opens the file closes it. A previous update of the NFS code broke the mechanics that prevented an NFS client from deleting a silly-renamed entry. This affected the "delete on last close" semantics and silly-renamed files could be deleted by any process while the files were open for I/O by another process. As a consequence, the process reading the file failed with the "ESTALE" error code. This update modifies the way the NFS code handles dentries of silly-renamed files and silly-renamed files can not be deleted until the last process that has the file open for I/O closes it.
BZ#920267
The NFSv4 code uses byte range locks to simulate the flock() function, which is used to apply or remove an exclusive advisory lock on an open file. However, using the NFSv4 byte range locks precludes a possibility to open a file with read-only permissions and subsequently to apply an exclusive advisory lock on the file. A previous patch broke a mechanism used to verify the mode of the open file. As a consequence, the system became unresponsive and the system logs filled with a "kernel: nfs4_reclaim_open_state: Lock reclaim failed!" error message if the file was open with read-only permissions and an attempt to apply an exclusive advisory lock was made. This update modifies the NFSv4 code to check the mode of the open file before attempting to apply the exclusive advisory lock. The "-EBADF" error code is returned if the type of the lock does not match the file mode.
BZ#921960
When running a high thread workload of small-sized files on an XFS file system, the system could become unresponsive or a kernel panic could occur. This occurred because the xfsaild daemon had a subtle code path that led to lock recursion on the xfsaild lock when a buffer in the AIL was already locked and an attempt was made to force the log to unlock it. This patch removes the dangerous code path and queues the log force to be invoked from a safe locking context with respect to xfsaild. This patch also fixes the race condition between buffer locking and buffer pinned state that exposed the original problem by rechecking the state of the buffer after a lock failure. The system no longer hangs and the kernel no longer panics in this scenario.
BZ#923850
Previously, the NFS Lock Manager (NLM) did not resend blocking lock requests after NFSv3 server reboot recovery. As a consequence, when an application was running on a NFSv3 mount and requested a blocking lock, the application received an "-ENOLCK" error. This patch ensures that NLM always resends blocking lock requests after the grace period has expired.
BZ#924838
A bug in the anon_vma lock in the mprotect() function could cause virtual memory area (vma) corruption. The bug has been fixed so that virtual memory area corruption no longer occurs in this scenario.
All users are advised to upgrade to these updated packages, which fix these bugs. The system must be rebooted for this update to take effect.
Updated kernel packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 6.
The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2012-3412, Important
A flaw was found in the way socket buffers (skb) requiring TSO (TCP segment offloading) were handled by the sfc driver. If the skb did not fit within the minimum-size of the transmission queue, the network card could repeatedly reset itself. A remote attacker could use this flaw to cause a denial of service.
Red Hat would like to thank Ben Hutchings of Solarflare for reporting this issue.

Bug Fixes

BZ#856316
In Fibre Channel fabrics with large zones, the automatic port rescan on incoming Extended Link Service (ELS) frames and any adapter recovery could cause high traffic, in particular if many Linux instances shared a host bus adapter (HBA), which is common on IBM System z architecture. This could lead to various failures; for example, names server requests, port or adapter recovery could fail. With this update, ports are re-scanned only when setting an adapter online or on manual user-triggered writes to the sysfs attribute "port_rescan".
BZ#856686
Under certain circumstances, a system crash could result in data loss on XFS file systems. If files were created immediately before the file system was left to idle for a long period of time and then the system crashed, those files could appear as zero-length once the file system was remounted. This occurred even if a sync or fsync was run on the files. This was because XFS was not correctly idling the journal, and therefore it incorrectly replayed the inode allocation transactions upon mounting after the system crash, which zeroed the file size. This problem has been fixed by re-instating the periodic journal idling logic to ensure that all metadata is flushed within 30 seconds of modification, and the journal is updated to prevent incorrect recovery operations from occurring.
BZ#856703
On architectures with the 64-bit cputime_t type, it was possible to trigger the "divide by zero" error, namely, on long-lived processes. A patch has been applied to address this problem, and the "divide by zero" error no longer occurs under these circumstances.
BZ#857012
The kernel provided by the Red Hat Enterprise Linux 6.3 release included an unintentional kernel ABI (kABI) breakage with regards to the "contig_page_data" symbol. Unfortunately, this breakage did not cause the checksums to change. As a result, drivers using this symbol could silently corrupt memory on the kernel. This update reverts the previous behavior.

Note

Any driver compiled with the "contig_page_data" symbol during the early release of Red Hat Enterprise Linux 6.3 needs to be recompiled again for this kernel.
BZ#857334
A race condition could occur between page table sharing and virtual memory area (VMA) teardown. As a consequence, multiple "bad pmd" message warnings were displayed and "kernel BUG at mm/filemap.c:129" was reported while shutting down applications that share memory segments backed by huge pages. With this update, the VM_MAYSHARE macro is explicitly cleaned during the unmap_hugepage_range() call under the i_mmap_lock. This makes VMA ineligible for sharing and avoids the race condition. After using shared segments backed by huge pages, applications like databases and caches shut down correctly, with no crash.
BZ#857854
A kernel panic could occur when using the be2net driver. This was because the Bottom Half (BF) was enabled even if the Interrupt ReQuest (IRQ) was already disabled. With this update, the BF is disabled in callers of the be_process_mcc() function and the kernel no longer crashes in this scenario.

Note

Note that, in certain cases, it is possible to experience the network card being unresponsive after installing this update. A future update will correct this problem.
BZ#858284
The Stream Control Transmission Protocol (SCTP) ipv6 source address selection logic did not take the preferred source address into consideration. With this update, the source address is chosen from the routing table by taking this aspect into consideration. This brings the SCTP source address selection on par with IPv4.
BZ#858285
Prior to this update, it was not possible to set IPv6 source addresses in routes as it was possible with IPv4. With this update, users can select the preferred source address for a specific IPv6 route with the "src" option of the "ip -6 route" command.
All users of kernel should upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.
Updated kernel packages that fix multiple security issues and several bugs are now available for Red Hat Enterprise Linux 6.
The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2012-2313, Low
A flaw was found in the way the Linux kernel's dl2k driver, used by certain D-Link Gigabit Ethernet adapters, restricted IOCTLs. A local, unprivileged user could use this flaw to issue potentially harmful IOCTLs, which could cause Ethernet adapters using the dl2k driver to malfunction (for example, losing network connectivity).
CVE-2012-2384, Moderate
An integer overflow flaw was found in the i915_gem_do_execbuffer() function in the Intel i915 driver in the Linux kernel. A local, unprivileged user could use this flaw to cause a denial of service. This issue only affected 32-bit systems.
CVE-2012-2390, Moderate
A memory leak flaw was found in the way the Linux kernel's memory subsystem handled resource clean up in the mmap() failure path when the MAP_HUGETLB flag was set. A local, unprivileged user could use this flaw to cause a denial of service.
CVE-2012-3430, Low
A flaw was found in the way the msg_namelen variable in the rds_recvmsg() function of the Linux kernel's Reliable Datagram Sockets (RDS) protocol implementation was initialized. A local, unprivileged user could use this flaw to leak kernel stack memory to user-space.
CVE-2012-3552, Moderate
A race condition was found in the way access to inet->opt ip_options was synchronized in the Linux kernel's TCP/IP protocol suite implementation. Depending on the network facing applications running on the system, a remote attacker could possibly trigger this flaw to cause a denial of service. A local, unprivileged user could use this flaw to cause a denial of service regardless of the applications the system runs.
Red Hat would like to thank Hafid Lin for reporting CVE-2012-3552, and Stephan Mueller for reporting CVE-2012-2313. The CVE-2012-3430 issue was discovered by the Red Hat InfiniBand team.

Bug Fixes

BZ#812962
Previously, after a crash, preparing to switch to the kdump kernel could in rare cases race with IRQ migration, causing a deadlock of the ioapic_lock variable. As a consequence, kdump became unresponsive. The race condition has been fixed, and switching to kdump no longer causes hangs in this scenario.
BZ#842757
The xmit packet size was previously 64K, exceeding the hardware capability of the be2net card because the size did not account for the Ethernet header. The adapter was therefore unable to process xmit requests exceeding this size, produced error messages and could become unresponsive. To prevent these problems, GSO (Generic Segmentation Offload) maximum size has been reduced to account for the Ethernet header.
BZ#842982
When the netconsole module was configured over bridge and the "service network restart" command was executed, a deadlock could occur, resulting in a kernel panic. This was caused by recursive rtnl locking by both bridge and netconsole code during network interface unregistration. With this update, the rtnl lock usage is fixed, and the kernel no longer crashes in this scenario.
BZ#842984
When using virtualization with the netconsole module configured over the main system bridge, guests could not be added to the bridge, because TAP interfaces did not support netpoll. This update adds support of netpoll to the TUN/TAP interfaces so that bridge devices in virtualization setups can use netconsole.
BZ#843102
Signed-unsigned values comparison could under certain circumstances lead to a superfluous reshed_task() routine to be called, causing several unnecessary cycles in the scheduler. This problem has been fixed, preventing the unnecessary cycles in the scheduler.
BZ#845464
If RAID1 or RAID10 was used under LVM or some other stacking block device, it was possible to enter a deadlock during a resync or recovery operation. Consequently, md RAID devices could become unresponsive on certain workloads. This update avoids the deadlock so that md RAID devices work as expected under these circumstances.
BZ#846216
Previously, soft interrupt requests (IRQs) under the bond_alb_xmit() function were locked even when the function contained soft IRQs that were disabled. This could cause a system to become unresponsive or terminate unexpectedly. With this update, such IRQs are no longer disabled, and the system no longer hangs or crashes in this scenario.
BZ#846832
Previously, the TCP socket bound to NFS server contained a stale skb_hints socket buffer. Consequently, kernel could terminate unexpectedly. A patch has been provided to address this issue and skb_hints is now properly cleared from the socket, thus preventing this bug.
BZ#846836
A race condition could occur due to incorrect locking scheme in the code for software RAID. Consequently, this could cause the mkfs utility to become unresponsive when creating an ext4 file system on software RAID5. This update introduces a locking scheme in the handle_stripe() function, which ensures that the race condition no longer occurs.
BZ#846838
When a device is added to the system at runtime, the AMD IOMMU driver initializes the necessary data structures to handle translation for it. Previously, however, the per-device dma_ops structure types were not changed to point to the AMD IOMMU driver, so mapping was not performed and direct memory access (DMA) ended with the IO_PAGE_FAULT message. This consequently led to networking problems. With this update, the structure types point correctly to the AMD IOMMU driver, and networking works as expected when the AMD IOMMU driver is used.
BZ#846839
Due to an error in the dm-mirror driver, when using LVM mirrors on disks with discard support (typically SSD disks), repairing such disks caused the system to terminate unexpectedly. The error in the driver has been fixed and repairing disks with discard support is now successful.
BZ#847042
On Intel systems with Pause Loop Exiting (PLE), or AMD systems with Pause Filtering (PF), it was possible for larger multi-CPU KVM guests to experience slowdowns and soft lock-ups. Due to a boundary condition in kvm_vcpu_on_spin, all the VCPUs could try to yield to VCPU0, causing contention on the run queue lock of the physical CPU where the guest's VCPU0 is running. This update eliminates the boundary condition in kvm_vcpu_on_spin.
BZ#847045
Previously, using the e1000e driver could lead to a kernel panic. This was caused by a NULL pointer dereference that occurred if the adapter was being closed and reset simultaneously. The source code of the driver has been modified to address this problem, and kernel no longer crashes in this scenario.
BZ#847727
On PowerPC architecture, the "top" utility displayed incorrect values for the CPU idle time, delays and workload. This was caused by a previous update that used jiffies for the I/O wait and idle time, but the change did not take into account that jiffies and CPU time are represented by different units. These differences are now taken into account, and the "top" utility displays correct values on PowerPC architecture.
BZ#847945
Due to a missing return statement, the nfs_attr_use_mounted_on_file() function returned a wrong value. As a consequence, redundant ESTALE errors could potentially be returned. This update adds the proper return statement to nfs_attr_use_mounted_on_file(), thus preventing this bug.

Note

This bug only affected NFS version 4 file systems.
BZ#849051
A deadlock sometimes occurred between the dlm_controld daemon closing a lowcomms connection through the configfs file system and the dlm_send process looking up the address for a new connection in configfs. With this update, the node addresses are saved within the lowcomms code so that the lowcomms work queue does not need to use configfs to get a node address.
BZ#849551
Performance of O_DSYNC on the GFS2 file system was affected when only data (not metadata such as file size) was dirtied as a result of a write system call. This was because O_DSYNC writes were always behaving in the same way as O_SYNC. With this update, O_DSYNC writes only write back data, if the inode's metadata is not dirty. This leads to a considerable performance improvement in this case. Note that this problem does not affect data integrity. The same issue also applies to the pairing of write and fdatasync calls.
BZ#851444
If a mirror or redirection action is configured to cause packets to go to another device, the classifier holds a reference count. However, it was previously assuming that the administrator cleaned up all redirections before removing. Packets were therefore dropped if the mirrored device was not present, and connectivity to the host could be lost. To prevent such problems, a notifier and cleanup are now run during the unregister action. Packets are not dropped if the a mirrored device is not present.
BZ#851445
The kernel contains a rule to blacklist direct memory access (DMA) modes for "2GB ATA Flash Disk" devices. However, this device ID string did not contain a space at the beginning of the name. Due to this, the rule failed to match the device and failed to disable DMA modes. With this update, the string correctly reads " 2GB ATA Flash Disk", and the rule can be matched as expected.
All users of kernel should upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.
Updated kernel packages that fix four bugs are now available for Red Hat Enterprise Linux 6.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Bug Fixes

BZ#836904
Previously, futex operations on read-only (RO) memory maps did not work correctly. This broke workloads that had one or more reader processes performing the FUTEX_WAIT operation on a futex within a read-only shared file mapping and a writer process that had a writable mapping performing the FUTEX_WAKE operation. With this update, the FUTEX_WAKE operation is performed with a RO MAP_PRIVATE mapping, and is successfully awaken if another process updates the region of the underlying mapped file.
BZ#837218
When removing a bonding module, the bonding driver uses code separate from the net device operations to clean up the VLAN code. Recent changes to the kernel introduced a bug which caused a kernel panic if the vlan module was removed after the bonding module had been removed. To fix this problem, the VLAN group removal operations found in the bonding kill_vid path are now duplicated in alternate paths which are used when removing a bonding module.
BZ#837227
The bonding method for adding VLAN Identifiers (VIDs) did not always add the VID to a slave VLAN group. When the NETIF_F_HW_VLAN_FILTER flag was not set on a slave, the bonding module could not add new VIDs to it. This could cause networking problems and the system to be unreachable even if NIC messages did not indicate any problems. This update changes the bond VID add path to always add a new VID to the slaves (if the VID does not exist). This ensures that networking problems no longer occur in this scenario.
BZ#837843
Previously, reference counting was imbalanced in the slave add and remove paths for bonding. If a network interface controller (NIC) did not support the NETIF_F_HW_VLAN_FILTER flag, the bond_add_vlans_on_slave() and bond_del_vlans_on_slave() functions did not work properly, which could lead to a kernel panic if the VLAN module was removed while running. The underlying source code for adding and removing a slave and a VLAN has been revised and now also contains a common path, so that kernel crashes no kernel no longer occur in the described scenario.
All users of kernel are advised to upgrade to these updated packages, which fix these bugs. The system must be rebooted for this update to take effect.
Updated kernel packages that fix three security issues and multiple bugs are now available for Red Hat Enterprise Linux 6.
The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2012-4398, Moderate
It was found that a deadlock could occur in the Out of Memory (OOM) killer. A process could trigger this deadlock by consuming a large amount of memory, and then causing request_module() to be called. A local, unprivileged user could use this flaw to cause a denial of service (excessive memory consumption).
CVE-2012-4461, Moderate
A flaw was found in the way the KVM (Kernel-based Virtual Machine) subsystem handled guests attempting to run with the X86_CR4_OSXSAVE CPU feature flag set. On hosts without the XSAVE CPU feature, a local, unprivileged user could use this flaw to crash the host system. (The "grep --color xsave /proc/cpuinfo" command can be used to verify if your system has the XSAVE CPU feature.)
CVE-2012-4530, Low
A memory disclosure flaw was found in the way the load_script() function in the binfmt_script binary format handler handled excessive recursions. A local, unprivileged user could use this flaw to leak kernel stack memory to user-space by executing specially-crafted scripts.
Red Hat would like to thank Tetsuo Handa for reporting CVE-2012-4398, and Jon Howell for reporting CVE-2012-4461.

Bug Fixes

BZ#846840
When an NFSv4 client received a read delegation, a race between the OPEN and DELEGRETURN operation could occur. If the DELEGRETURN operation was processed first, the NFSv4 client treated the delegation returned by the following OPEN as a new delegation. Also, the NFSv4 client did not correctly handle errors caused by requests that used a bad or revoked delegation state ID. As a result, applications running on the client could receive spurious EIO errors. This update applies a series of patches that fix the NFSv4 code so an NFSv4 client recovers correctly in the described situations instead of returning errors to applications.
BZ#865305
Filesystem in Userspace (FUSE) did not implement scatter-gather direct I/O optimally. Consequently, the kernel had to process an extensive number of FUSE requests, which had a negative impact on system performance. This update applies a set of patches which improves internal request management for other features, such as readahead. FUSE direct I/O overhead has been significantly reduced to minimize negative effects on system performance.
BZ#876090
In case of a regular CPU hot plug event, the kernel does not keep the original cpuset configuration and can reallocate running tasks to active CPUs. Previously, the kernel treated switching between suspend and resume modes as a regular CPU hot plug event, which could have a significant negative impact on system performance in certain environments such as SMP KVM virtualization. When resuming an SMP KVM guest from suspend mode, the libvirtd daemon and all its child processes were pinned to a single CPU (the boot CPU) so that all VMs used only the single CPU. This update applies a set of patches which ensure that the kernel does not modify cpusets during suspend and resume operations. The system is now resumed in the exact state before suspending without any performance decrease.
BZ#878774
Previously, the kernel had no way to distinguish between a device I/O failure due to a transport problem and a failure as a result of command timeout expiration. I/O errors always resulted in a device being set offline and the device had to be brought online manually even though the I/O failure occured due to a transport problem. With this update, the SCSI driver has been modified and a new SDEV_TRANSPORT_OFFLINE state has been added to help distinguish transport problems from another I/O failure causes. Transport errors are now handled differently and storage devices can now recover from these failures without user intervention.
BZ#880085
Previously, the IP over Infiniband (IPoIB) driver maintained state information about neighbors on the network by attaching it to the core network's neighbor structure. However, due to a race condition between the freeing of the core network neighbor struct and the freeing of the IPoIB network struct, a use after free condition could happen, resulting in either a kernel oops or 4 or 8 bytes of kernel memory being zeroed when it was not supposed to be. These patches decouple the IPoIB neighbor struct from the core networking stack's neighbor struct so that there is no race between the freeing of one and the freeing of the other.
BZ#880928
When a new rpc_task is created, the code takes a reference to rpc_cred and sets the task->tk_cred pointer to it. After the call completes, the resources held by the rpc_task are freed. Previously, however, after the rpc_cred was released, the pointer to it was not zeroed out. This led to an rpc_cred reference count underflow, and consequently to a kernel panic. With this update, the pointer to rpc_cred is correctly zeroed out, which prevents a kernel panic from occurring in this scenario.
BZ#884422
Previously, the HP Smart Array driver (hpsa) used the target reset functionality. However, HP Smart Array logical drives do not support the target reset functionality. Therefore, if the target reset failed, the logical drive was taken offline with a file system error. The hpsa driver has been updated to use the LUN reset functionality instead of target reset, which is supported by these drives.
BZ#886618
The bonding driver previously did not honor the maximum Generic Segmentation Offload (GSO) length of packets and segments requested by the underlying network interface. This caused the firmware of the underlying NIC, such as be2net, to become unresponsive. This update modifies the bonding driver to set up the lowest gso_max_size and gso_max_segs values of network devices while attaching and detaching the devices as slaves. The network drivers no longer hangs and network traffic now proceeds as expected in setups using a bonding interface.
BZ#886760
Previously, the interrupt handlers of the qla2xxx driver could clear pending interrupts right after the IRQ lines were attached during system start-up. Consequently, the kernel could miss the interrupt that reported completion of the link initialization, and the qla2xxx driver then failed to detect all attached LUNs. With this update, the qla2xxx driver has been modified to no longer clear interrupt bits after attaching the IRQ lines. The driver now correctly detects all attached LUNs as expected.
BZ#888215
When TCP segment offloading (TSO) or jumbo packets are used on the Broadcom BCM5719 network interface controller (NIC) with multiple TX rings, small packets can be starved for resources by the simple round-robin hardware scheduling of these TX rings, thus causing lower network performance. To ensure reasonable network performance for all NICs, multiple TX rings are now disabled by default.
BZ#888818
Due to insufficient handling of a dead Input/Output Controller (IOC), the mpt2sas driver could fail Enhanced I/O Error Handling (EEH) recovery for certain PCI bus failures on 64-bit IBM PowerPC machines. With this update, when a dead IOC is detected, EEH recovery routine has more time to resolve the failure and the controller in a non-operational state is removed.
BZ#891580
A possible race between the n_tty_read() and reset_buffer_flags() functions could result in a NULL pointer dereference in the n_tty_read() function under certain circumstances. As a consequence, a kernel panic could have been triggered when interrupting a current task on a serial console. This update modifies the tty driver to use a spin lock to prevent functions from a parallel access to variables. A NULL pointer dereference causing a kernel panic can no longer occur in this scenario.
All users should upgrade to these updated packages, which contain backported patches to correct these issues and bugs. The system must be rebooted for this update to take effect.
Updated kernel packages that fix two security issues and several bugs are now available for Red Hat Enterprise Linux 6.
The Red Hat Security Response Team has rated this update as having important security impact. Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2012-2744, Important
A NULL pointer dereference flaw was found in the nf_ct_frag6_reasm() function in the Linux kernel's netfilter IPv6 connection tracking implementation. A remote attacker could use this flaw to send specially-crafted packets to a target system that is using IPv6 and also has the nf_conntrack_ipv6 kernel module loaded, causing it to crash.
CVE-2012-2745, Moderate
A flaw was found in the way the Linux kernel's key management facility handled replacement session keyrings on process forks. A local, unprivileged user could use this flaw to cause a denial of service.
Red Hat would like to thank an anonymous contributor working with the Beyond Security SecuriTeam Secure Disclosure program for reporting CVE-2012-2744.

Bug Fixes

BZ#832359
Previously introduced firmware files required for new Realtek chipsets contained an invalid prefix ("rtl_nic_") in the file names, for example "/lib/firmware/rtl_nic/rtl_nic_rtl8168d-1.fw". This update corrects these file names. For example, the aforementioned file is now correctly named "/lib/firmware/rtl_nic/rtl8168d-1.fw".
BZ#832363
This update blacklists the ADMA428M revision of the 2GB ATA Flash Disk device. This is due to data corruption occurring on the said device when the Ultra-DMA 66 transfer mode is used. When the "libata.force=5:pio0,6:pio0" kernel parameter is set, the aforementioned device works as expected.
BZ#832365
On Red Hat Enterprise Linux 6, mounting an NFS export from a Windows 2012 server failed due to the fact that the Windows server contains support for the minor version 1 (v4.1) of the NFS version 4 protocol only, along with support for versions 2 and 3. The lack of the minor version 0 (v4.0) support caused Red Hat Enterprise Linux 6 clients to fail instead of rolling back to version 3 as expected. This update fixes this bug and mounting an NFS export works as expected.
BZ#833034
On ext4 file systems, when fallocate() failed to allocate blocks due to the ENOSPC condition (no space left on device) for a file larger than 4 GB, the size of the file became corrupted and, consequently, caused file system corruption. This was due to a missing cast operator in the "ext4_fallocate()" function. With this update, the underlying source code has been modified to address this issue, and file system corruption no longer occurs.
Users should upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.
Updated kernel packages that fix two bugs are now available for Red Hat Enterprise Linux 6.
The kernel packages contain the Linux kernel, the core of any Linux operating system.
When an NTP server asserts the STA_INS flag (Leap Second Insert), the kernel starts an hrtimer (high-resolution timer) with a countdown clock. This hrtimer expires at end of the current month, midnight UTC, and inserts a second into the kernel timekeeping structures. A scheduled leap second occurred on June 30 2012 midnight UTC.

Bug Fixes

BZ#840950
Previously in the kernel, when the leap second hrtimer was started, it was possible that the kernel livelocked on the xtime_lock variable. This update fixes the problem by using a mixture of separate subsystem locks (timekeeping and ntp) and removing the xtime_lock variable, thus avoiding the livelock scenarios that could occur in the kernel.
BZ#847366
After the leap second was inserted, applications calling system calls that used futexes consumed almost 100% of available CPU time. This occurred because the kernel's timekeeping structure update did not properly update these futexes. The futexes repeatedly expired, re-armed, and then expired immediately again. This update fixes the problem by properly updating the futex expiration times by calling the clock_was_set_delayed() function, an interrupt-safe method of the clock_was_set() function.
All users are advised to upgrade to these updated packages, which fix these bugs. The system must be rebooted for this update to take effect.
Updated kernel packages that fix two security issues and several bugs are now available for Red Hat Enterprise Linux 6.
The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2012-2383, Moderate
An integer overflow flaw was found in the i915_gem_execbuffer2() function in the Intel i915 driver in the Linux kernel. A local, unprivileged user could use this flaw to cause a denial of service. This issue only affected 32-bit systems.
CVE-2011-1078, Low
A missing initialization flaw was found in the sco_sock_getsockopt_old() function in the Linux kernel's Bluetooth implementation. A local, unprivileged user could use this flaw to cause an information leak.
Red Hat would like to thank Vasiliy Kulikov of Openwall for reporting the CVE-2011-1078 issue.

Bug Fixes

BZ#832360
A bug in the writeback livelock avoidance scheme could result in some dirty data not being written to disk during a sync operation. In particular, this could occasionally occur at unmount time, when previously written file data was not synced, and was unavailable after the file system was remounted. Patches have been applied to address this issue, and all dirty file data is now synced to disk at unmount time.
BZ#838821
During the update of the be2net driver between the Red Hat Enterprise Linux 6.1 and 6.2, the NETIF_F_GRO flag was incorrectly removed, and the GRO (Generic Receive Offload) feature was therefore disabled by default. In OpenVZ kernels based on Red Hat Enterprise Linux 6.2, this led to a significant traffic decrease. To prevent this problem, the NETIF_F_GRO flag has been included in the underlying source code.
BZ#840023
Previously, the size of the multicast IGMP (Internet Group Management Protocol) snooping hash table for a bridge was limited to 256 entries even though the maximum is 512. This was due to the hash table size being incorrectly compared to the maximum hash table size, hash_max, and the following message could have been produced by the kernel:
Multicast hash table maximum reached, disabling snooping: vnet1, 512
With this update, the hash table value is correctly compared to the hash_max value, and the error message no longer occurs under these circumstances.
BZ#840052
In the ext4 file system, splitting an unwritten extent while using Direct I/O could fail to mark the modified extent as dirty, resulting in multiple extents claiming to map the same block. This could lead to the kernel or fsck reporting errors due to multiply claimed blocks being detected in certain inodes. In the ext4_split_unwritten_extents() function used for Direct I/O, the buffer which contains the modified extent is now properly marked as dirty in all cases. Errors due to multiply claimed blocks in inodes should no longer occur for applications using Direct I/O.
BZ#840156
With certain switch peers and firmware, excessive link flaps could occur due to the way DCBX (Data Center Bridging Exchange) was handled. To prevent link flaps, changes were made to examine the capabilities in more detail and only initialize hardware if the capabilities have changed.
BZ#841406
The CONFIG_CFG80211_WEXT configuration option previously defined in the KConfig of the ipw2200 driver was removed with a recent update. This led to a build failure of the driver. The driver no longer depends on the CONFIG_CFG80211_WEXT option, so it can build successfully.
BZ#841411
Migrating virtual machines from Intel hosts that supported the VMX "Unrestricted Guest" feature to older hosts without this feature could result in kvm returning the "unhandled exit 80000021" error for guests in real mode. The underlying source code has been modified so that migration completes successfully on hosts where "Unrestricted Guest" is disabled or not supported.
BZ#841579
Previous update changed the /proc/stat code to use the get_cpu_idle_time_us() and get_cpu_iowait_time_us() macros if dynamic ticks are enabled in the kernel. This could lead to problems on IBM System z architecture that defines the arch_idle_time() macro. For example, executing the "vmstat" command could fail with "Floating point exception" followed by a core dump. The underlying source code has been modified so that the arch_idle_time() macro is used for idle and iowait times, which prevents the mentioned problem.
BZ#842429
Bond masters and slaves now have separate VLAN groups. As such, if a slave device incurred a network event that resulted in a failover, the VLAN device could process this event erroneously. With this update, when a VLAN is attached to a master device, it ignores events generated by slave devicec so that the VLANs do not go down until the bond master does.
Users should upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.
Updated kernel packages that fix multiple security issues, numerous bugs, and add one enhancement are now available for Red Hat Enterprise Linux 6.
The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2012-2375, Moderate
It was found that the RHSA-2012:0862 update did not correctly fix the CVE-2011-4131 issue. A malicious Network File System version 4 (NFSv4) server could return a crafted reply to a GETACL request, causing a denial of service on the client.
CVE-2012-4565, Moderate
A divide-by-zero flaw was found in the TCP Illinois congestion control algorithm implementation in the Linux kernel. If the TCP Illinois congestion control algorithm were in use (the sysctl net.ipv4.tcp_congestion_control variable set to "illinois"), a local, unprivileged user could trigger this flaw and cause a denial of service.
CVE-2012-5517, Moderate
A NULL pointer dereference flaw was found in the way a new node's hot added memory was propagated to other nodes' zonelists. By utilizing this newly added memory from one of the remaining nodes, a local, unprivileged user could use this flaw to cause a denial of service.
CVE-2012-2100, Low
It was found that the initial release of Red Hat Enterprise Linux 6 did not correctly fix the CVE-2009-4307 issue, a divide-by-zero flaw in the ext4 file system code. A local, unprivileged user with the ability to mount an ext4 file system could use this flaw to cause a denial of service.
CVE-2012-4444, Low
A flaw was found in the way the Linux kernel's IPv6 implementation handled overlapping, fragmented IPv6 packets. A remote attacker could potentially use this flaw to bypass protection mechanisms (such as a firewall or intrusion detection system (IDS)) when sending network packets to a target system.
Red Hat would like to thank Antonios Atlasis working with Beyond Security's SecuriTeam Secure Disclosure program and Loganaden Velvindron of AFRINIC for reporting CVE-2012-4444. The CVE-2012-2375 issue was discovered by Jian Li of Red Hat, and CVE-2012-4565 was discovered by Rodrigo Freire of Red Hat.

Bug Fixes

BZ#853950
The kernel allows high priority real time tasks, such as tasks scheduled with the SCHED_FIFO policy, to be throttled. Previously, the CPU stop tasks were scheduled as high priority real time tasks and could be thus throttled accordingly. However, the replenishment timer, which is responsible for clearing a throttle flag on tasks, could be pending on the just disabled CPU. This could lead to a situation that the throttled tasks were never scheduled to run. Consequently, if any of such tasks was needed to complete the CPU disabling, the system became unresponsive. This update introduces a new scheduler class, which gives a task the highest possible system priority and such a task cannot be throttled. The stop-task scheduling class is now used for the CPU stop tasks, and the system shutdown completes as expected in the scenario described.
BZ#864826
A kernel panic occurred when the size of a block device was changed and an I/O operation was issued at the same time. This was because the direct and non-direct I/O code was written with the assumption that the block size would not change. This update introduces a new read-write lock, bd_block_size_semaphore. The lock is taken for read during I/O operations and for write when changing the block size of a device. As a result, block size cannot be changed while I/O is being submitted. This prevents the kernel from crashing in the described scenario.
BZ#866470
A previous kernel update introduced a bug that caused RAID0 and linear arrays larger than 4 TB to be truncated to 4 TB when using 0.90 metadata. The underlying source code has been modified so that 0.90 RAID0 and linear arrays larger than 4 TB are no longer truncated in the md RAID layer.
BZ#866795
The mlx4 driver must program the mlx4 card so that it is able to resolve which MAC addresses to listen to, including multicast addresses. Therefore, the mlx4 card keeps a list of trusted MAC addresses. The driver used to perform updates to this list on the card by emptying the entire list and then programming in all of the addresses. Thus, whenever a user added or removed a multicast address or put the card into or out of promiscuous mode, the card's entire address list was re-written. This introduced a race condition, which resulted in a packet loss if a packet came in on an address the card should be listening to, but had not yet been reprogrammed to listen to. With this update, the driver no longer rewrites the entire list of trusted MAC addresses on the card but maintains a list of addresses that are currently programmed into the card. On address addition, only the new address is added to the end of the list, and on removal, only the to-be-removed address is removed from the list. The mlx4 card no longer experiences the described race condition and packets are no longer dropped in this scenario.
BZ#871854
If there are no active threads using a semaphore, blocked threads should be unblocked. Previously, the R/W semaphore code looked for a semaphore counter as a whole to reach zero - which is incorrect because at least one thread is usually queued on the semaphore and the counter is marked to reflect this. As a consequence, the system could become unresponsive when an application used direct I/O on the XFS file system. With this update, only the count of active semaphores is checked, thus preventing the hang in this scenario.
BZ#874022
Due to an off-by-one error in a test condition in the bnx2x_start_xmit and bnx2x_tx_int functions, the TX queue of a NIC could, under some circumstances, be prevented from being resumed. Consequently, NICs using the bnx2x driver, such as Broadcom NetXtreme II 10G network devices, went offline. To bring the NIC back online, the bnx2x module had to be reloaded. This update corrects the test condition in the mentioned functions and the NICs using the bnx2x driver work as expected in the described scenario.
BZ#876088
If an abort request times out to the virtual Fibre Channel adapter, the ibmvfc driver initiates a reset of the adapter. Previously, however, the ibmvfc driver incorrectly returned success to the eh_abort handler and then sent a response to the same command, which led to a kernel oops on IBM System p machines. This update ensures that both the abort request and the request being aborted are completed prior to exiting the en_abort handler, and the kernel oops no longer occurs in this scenario.
BZ#876101
The hugetlbfs file system implementation was missing a proper lock protection of enqueued huge pages at the gather_surplus_pages() function. Consequently, the hstate.hugepages_freelist list became corrupted, which caused a kernel panic. This update adjusts the code so that the used spinlock protection now assures atomicity and safety of enqueued huge pages when handling hstate.hugepages_freelist. The kernel no longer panics in this scenario.
BZ#876487
A larger command descriptor block (CDB) is allocated for devices using Data Integrity Field (DIF) type 2 protection. The CDB was being freed in the sd_done() function, which resulted in a kernel panic if the command had to be retried in certain error recovery cases. With this update, the larger CDB is now freed in the sd_unprep_fn() function instead. This prevents the kernel panic from occurring.
BZ#876491
The previous implementation of socket buffers (SKBs) allocation for a NIC was node-aware, that is, memory was allocated on the node closest to the NIC. This increased performance of the system because all DMA transfer was handled locally. This was a good solution for networks with a lower frame transmitting rate where CPUs of the local node handled all the traffic of the single NIC well. However, when using 10Gb Ethernet devices, CPUs of one node usually do not handle all the traffic of a single NIC efficiently enough. Therefore, system performance was poor even though the DMA transfer was handled by the node local to the NIC. This update modifies the kernel to allow SKBs to be allocated on a node that runs applications receiving the traffic. This ensures that the NIC's traffic is handled by as many CPUs as needed, and since SKBs are accessed very frequently after allocation, the kernel can now operate much more efficiently even though the DMA can be transferred cross-node.
BZ#876493
When performing PCI device assignment on AMD systems, a virtual machine using the assigned device could not be able to boot, as the device had failed the assignment, leaving the device in an unusable state. This was due to an improper range check that omitted the last PCI device in a PCI subsystem or tree. The check has been fixed to include the full range of PCI devices in a PCI subsystem or tree. This bug fix avoids boot failures of a virtual machine when the last device in a PCI subsystem is assigned to a virtual machine on an AMD host system.
BZ#876496
The mmap_rnd() function is expected to return a value in the [0x00000000 .. 0x000FF000] range on 32-bit x86 systems. This behavior is used to randomize the base load address of shared libraries by a bug fix resolving the CVE-2012-1568 issue. However, due to a signedness bug, the mmap_rnd() function could return values outside of the intended scope. Consequently, the shared libraries base address could be less than one megabyte. This could cause binaries that use the MAP_FIXED mappings in the first megabyte of the process address space (typically, programs using vm86 functionality) to work incorrectly. This update modifies the mmap_rnd() function to no longer cast values returned by the get_random_int() function to the long data type. The aforementioned binaries now work correctly in this scenario.
BZ#876499
Previously, XFS could, under certain circumstances, incorrectly read metadata from the journal during XFS log recovery. As a consequence, XFS log recovery terminated with an error message and prevented the file system from being mounted. This problem could result in a loss of data if the user forcibly "zeroed" the log to allow the file system to be mounted. This update ensures that metadata is read correctly from the log so that journal recovery completes successfully and the file system mounts as expected.
BZ#876549
Some BIOS firmware versions could leave the "Frame Start Delay" bits of the PIPECONF register in test mode on selected Intel chipsets. Consequently, video output on certain Lenovo laptop series, such as T41x or T42x, became corrupted (for example, the screen appeared to be split and shifted to the right) after upgrading VBIOS from version 2130 to 2132. This update corrects the problem by resetting the "Frame Start Delay" bits for the normal operation use in the DRM driver. Video output of the previously affected Lenovo models is now correct.

Enhancement

BZ#877950
The INET socket interface has been modified to send a warning message when the ip_options structure is allocated directly by a third-party module using the kmalloc() function.
Users should upgrade to these updated kernel packages, which contain backported patches to correct these issues, fix these bugs and add this enhancement. The system must be rebooted for this update to take effect.
Updated kernel packages that fix multiple security issues and several bugs are now available for Red Hat Enterprise Linux 6.
The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2012-2133, Moderate
A use-after-free flaw was found in the Linux kernel's memory management subsystem in the way quota handling for huge pages was performed. A local, unprivileged user could use this flaw to cause a denial of service or, potentially, escalate their privileges.
CVE-2012-3511, Moderate
A use-after-free flaw was found in the madvise() system call implementation in the Linux kernel. A local, unprivileged user could use this flaw to cause a denial of service or, potentially, escalate their privileges.
CVE-2012-1568, Low
It was found that when running a 32-bit binary that uses a large number of shared libraries, one of the libraries would always be loaded at a predictable address in memory. An attacker could use this flaw to bypass the Address Space Layout Randomization (ASLR) security feature.
CVE-2012-3400, Low
Buffer overflow flaws were found in the udf_load_logicalvol() function in the Universal Disk Format (UDF) file system implementation in the Linux kernel. An attacker with physical access to a system could use these flaws to cause a denial of service or escalate their privileges.
Red Hat would like to thank Shachar Raindel for reporting CVE-2012-2133.

Bug Fixes

BZ#865713
Previously, the I/O watchdog feature was disabled when Intel Enhanced Host Controller Interface (EHCI) devices were detected. This could cause incorrect detection of USB devices upon addition or removal. Also, in some cases, even though such devices were detected properly, they were non-functional. The I/O watchdog feature can now be enabled on the kernel command line, which improves hardware detection on underlying systems.
BZ#864821
The usb_device_read() routine used the bus->root_hub pointer to determine whether or not the root hub was registered. However, this test was invalid because the pointer was set before the root hub was registered and remained set even after the root hub was unregistered and deallocated. As a result, the usb_device_read() routine accessed freed memory, causing a kernel panic; for example, on USB device removal. With this update, the hcs->rh_registered flag - which is set and cleared at the appropriate times - is used in the test, and the kernel panic no longer occurs in this scenario.
BZ#853257
Previously, when a server attempted to shut down a socket, the svc_tcp_sendto() function set the XPT_CLOSE variable if the entire reply failed to be transmitted. However, before XPT_CLOSE could be acted upon, other threads could send further replies before the socket was really shut down. Consequently, data corruption could occur in the RPC record marker. With this update, send operations on a closed socket are stopped immediately, thus preventing this bug.
BZ#853943
Previously, a race condition existed whereby device open could race with device removal (for example when hot-removing a storage device), potentially leading to a kernel panic. This was due a use-after-free error in the block device open patch, which has been corrected by not referencing the "disk" pointer after it has been passed to the module_put() function.
BZ#854476
Sometimes, the crypto allocation code could become unresponsive for 60 seconds or multiples thereof due to an incorrect notification mechanism. This could cause applications, like openswan, to become unresponsive. The notification mechanism has been improved to avoid such hangs.
BZ#856106
Traffic to the NFS server could trigger a kernel oops in the svc_tcp_clear_pages() function. The source code has been modified, and the kernel oops no longer occurs in this scenario.
BZ#860784
When a device was registered to a bus, a race condition could occur between the device being added to the list of devices of the bus and binding the device to a driver. As a result, the device could already be bound to a driver which led to a warning and incorrect reference counting, and consequently to a kernel panic on device removal. To avoid the race condition, this update adds a check to identify an already bound device.
BZ#865308
When I/O is issued through blk_execute_rq(), the blk_execute_rq_nowait() routine is called to perform various tasks. At first, the routine checks for a dead queue. Previously, however, if a dead queue was detected, the blk_execute_rq_nowait() function did not invoke the done() callback function. This resulted in blk_execute_rq() being unresponsive when waiting for completion, which had never been issued. To avoid such hangs, the rq->end_io pointer is initialized to the done() callback before the queue state is verified.
BZ#860942
The Out of Memory (OOM) killer killed processes outside of a memory cgroup when one or more processes inside that memory cgroup exceeded the "memory.limit_in_bytes" value. This was because when a copy-on-write fault happened on a Transparent Huge Page (THP), the 2 MB THP caused the cgroup to exceed the memory.limit_in_bytes value but the individual 4 KB page was not exceeded. With this update, the 2 MB THP is correctly split into 4 KB pages when the memory.limit_in_bytes value is exceeded. The OOM kill is delivered within the memory cgroup; tasks outside the memory cgroups are no longer killed by the OOM killer.
BZ#857055
An unnecessary check for the RXCW.CW bit could cause the Intel e1000e NIC (Network Interface Controller) to not work properly. The check has been removed so that the Intel e1000e NIC now works as expected.
BZ#860640
A kernel oops could occur due to a NULL pointer dereference upon USB device removal. The NULL pointer dereference has been fixed and the kernel no longer crashes in this scenario.
BZ#864827
Previously, a use-after-free bug in the usbhid code caused a NULL pointer dereference. Consequent kernel memory corruption resulted in a kernel panic and could cause data loss. This update adds a NULL check to avoid these problems.
BZ#841667
USB Request Blocks (URBs) coming from user space were not allowed to have transfer buffers larger than an arbitrary maximum. This could lead to various problems; for example, attempting to redirect certain USB mass-storage devices could fail. To avoid such problems, programs are now allowed to submit URBs of any size; if there is not sufficient contiguous memory available, the submission fails with an ENOMEM error. In addition, to prevent programs from submitting a lot of small URBs and so using all the DMA-able kernel memory, this update also replaces the old limits on individual transfer buffers with a single global limit of 16MB on the total amount of memory in use by USB file system (usbfs).
BZ#841824
A USB Human Interface Device (HID) can be disconnected at any time. If this happened right before or while the hiddev_ioctl() call was in progress, hiddev_ioctl() attempted to access the invalid hiddev->hid pointer. When the HID device was disconnected, the hiddev_disconnect() function called the hid_device_release() function, which frees the hid_device structure type, but did not set the hiddev->hid pointer to NULL. If the deallocated memory region was re-used by the kernel, a kernel panic or memory corruption could occur. The hiddev->exist flag is now checked while holding the existancelock and hid_device is used only if such a device exists. As a result, the kernel no longer crashes in this scenario.
BZ#863147
The MAC address stored in the driver's private structure is of the unsigned character data type but parameters of the strlcpy() function are of the signed character data type. This conversion of data types led to change in the value. This changed value was passed to the upper layer and garbage characters were displayed when running the "iscsiadm -m iface" command. Consequently, the garbage characters in the MAC address led to boot failures of iSCSI devices. MAC addresses are now formatted using the sysfs_format_mac() function rather than strlcpy(), which prevents the described problems.
BZ#861953
It is possible to receive data on multiple transports. Previously, however, data could be selectively acknowledged (SACKed) on a transport that had never received any data. This was against the SHOULD requirement in section 6.4 of the RFC 2960 standard. To comply with this standard, bundling of SACK operations is restricted to only those transports which have moved the ctsn of the association forward since the last sack. As a result, only outbound SACKs on a transport that has received a chunk since the last SACK are bundled.
BZ#861390
Bugs in the lpfs driver caused disruptive logical unit resets during fabric fault testing. The underlying source code has been modified so that the problem no longer occurs.
BZ#852450
Previously, bnx2x devices did not disable links with a large number of RX errors and overruns, and such links could still be detected as active. This prevented the bonding driver from failing over to a working link. This update restores remote-fault detection, which periodically checks for remote faults on the MAC layer. In case the physical link appears to be up but an error occurs, the link is disabled. Once the error is cleared, the link is brought up again.
BZ#860787
Various race conditions that led to indefinite log reservation hangs due to xfsaild "idle" mode occurred in XFS file system. This could lead to certain tasks being unresponsive; for example, the cp utility could become unresponsive on heavy workload. This update improves the Active Item List (AIL) pushing logic in xfsaild. Also, the log reservation algorithm and interactions with xfsaild have been improved. As a result, the aforementioned problems no longer occur in this scenario.
BZ#858955
On dual port Mellanox hardware, the mlx4 driver was adding promiscuous mode to the correct port, but when attempting to remove promiscuous mode from a port, it always tried to remove it from port one. It was therefore impossible to remove promiscuous mode from the second port, and promiscuous mode was incorrectly removed from port one even if it was not intended. With this update, the driver now properly attempts to remove promiscuous mode from port two when needed.
BZ#858956
Mellanox hardware keeps a separate list of Ethernet hardware addresses it listens to depending on whether the Ethernet hardware address is unicast or multicast. Previously, the mlx4 driver was incorrectly adding multicast addresses to the unicast list. This caused unstable behavior in terms of whether or not the hardware would have actually listened to the addresses requested. This update fixes the problem by always putting multicast addresses on the multicast list and vice versa.
BZ#859326
If a dirty GFS2 inode was being deleted but was in use by another node, its metadata was not written out before GFS2 checked for dirty buffers in the gfs2_ail_flush() function. GFS2 was relying on the inode_go_sync() function to write out the metadata when the other node tried to free the file. However, this never happened because GFS2 failed the error check. With this update, the inode is written out before calling the gfs2_ail_flush() function. If a process has the PF_MEMALLOC flag set, it does not start a new transaction to update the access time when it writes out the inode. The inode is marked as dirty to make sure that the access time is updated later unless the inode is being freed.
BZ#859436
In a previous release of Red Hat Enterprise Linux, the new Mellanox packet steering architecture had been intentionally left out of the Red Hat kernel. With Red Hat Enterprise Linux 6.3, the new Mellanox packet steering architecture was merged into Red Hat Mellanox driver. One merge detail was missing, and as a result, the multicast promiscuous flag on an interface was not checked during an interface reset to see if the flag was on prior to the reset and should be re-enabled after the reset. This update fixes the problem, so if an adapter is reset and the multicast promiscuous flag was set prior to the reset, the flag is now still set after the reset.
BZ#860165
Previously, the default minimum entitled capacity of a virtual processor was 10%. This update changes the PowerPC architecture vector to support a lower minimum virtual processor capacity of 1%.
BZ#858954
Previously, a cgroup or its hierarchy could only be modified under the cgroup_mutex master lock. This introduced a locking dependency on cred_guard_mutex from cgroup_mutex and completed a circular dependency, which involved cgroup_mutex, namespace_sem and workqueue, and led to a deadlock. As a consequence, many processes were unresponsive, and the system could be eventually unusable. This update introduces a new mutex, cgroup_root_mutex, which protects cgroup root modifications and is now used by mount options readers instead of the master lock. This breaks the circular dependency and avoids the deadlock.
All users of kernel should upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.
Updated kernel packages that fix two security issues, address several hundred bugs, and add numerous enhancements are now available as part of the ongoing support and maintenance of Red Hat Enterprise Linux version 6. This is the third regular update.
The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2011-1083, Moderate
A flaw was found in the way the Linux kernel's Event Poll (epoll) subsystem handled large, nested epoll structures. A local, unprivileged user could use this flaw to cause a denial of service.
CVE-2011-4131, Moderate
A malicious Network File System version 4 (NFSv4) server could return a crafted reply to a GETACL request, causing a denial of service on the client.
Red Hat would like to thank Nelson Elhage for reporting CVE-2011-1083, and Andy Adamson for reporting CVE-2011-4131.

Bug Fixes

BZ#824025
Hotplugging SATA disks did not work properly and the system experienced various issues when hotplugging such devices. This update fixes several hotplugging issues in the kernel and SAS hotplugging now works as expected.
BZ#782374
Due to a bug in the hid_reset() function, a deadlock could occur when a Dell iDRAC controller was reset. Consequently, its USB keyboard or mouse device became unresponsive. A patch that fixes the underlying code has been provided to address this bug and the hangs no longer occur in the described scenario.
BZ#781531
The AMD IOMMU driver used wrong shift direction in the alloc_new_range() function. Consequently, the system could terminate unexpectedly or become unresponsive. This update fixes the code and crashes and hangs no longer occur in the described scenario.
BZ#781524
Previously, the AMD IOMMU (input/output memory management unit) driver could use the MSI address range for DMA (direct memory access) addresses. As a consequence, DMA could fail and spurious interrupts would occur if this address range was used. With this update, the MSI address range is reserved to prevent the driver from allocating wrong addresses and DMA is now assured to work as expected in the described scenario.
BZ#773705
Windows clients never send write requests larger than 64 KB but the default size for write requests in Common Internet File System (CIFS) was set to a much larger value. Consequently, write requests larger than 64 KB caused various problems on certain third-party servers. This update lowers the default size for write requests to prevent this bug. The user can override this value to a larger one to get better performance.
BZ#773522
Due to a race condition between the notify_on_release() function and task movement between cpuset or memory cgroup directories, a system deadlock could occur. With this update, the cgroup_wq cgroup has been created and both async_rebuild_domains() and check_for_release() functions used for task movements use it, thus fixing this bug.
BZ#773517
Due to invalid calculations of the vruntime variable along with task movement between cgroups, moving tasks between cgroups could cause very long scheduling delays. This update fixes this problem by setting the cfs_rq and curr parameters after holding the rq->lock lock.
BZ#784671
The kernel code checks for conflicts when an application requests a specific port. If there is no conflict, the request is granted. However, the port auto-selection done by the kernel failed when all ports were bound, even if there was an available port with no conflicts. With this update, the port auto-selection code has been fixed to properly use ports with no conflicts.
BZ#784758
A bug in the try_to_wake_up() function could cause status change from TASK_DEAD to TASK_RUNNING in a race condition with an SMI (system management interrupt) or a guest environment of a virtual machine. As a consequence, the exited task was scheduled again and a kernel panic occurred. This update fixes the race condition in the do_exit() function and the panic no longer occurs in the described scenario.
BZ#785891
Previously, if more than a certain number of qdiscs (Classless Queuing Disciplines) using the autohandle mechanism were allocated a soft lock-up error occurred. This update fixes the maximum loop count and adds the cond_resched() call in the loop, thus fixing this bug.
BZ#785959
Prior to this update, the find_busiest_group() function used sched_group->cpu_power in the denominator of a fraction with a value of 0. Consequently, a kernel panic occurred. This update prevents the divide by zero in the kernel and the panic no longer occurs.
BZ#772874
In the Common Internet File System (CIFS), the oplock break jobs and async callback handlers both use the SLOW-WORK workqueue, which has a finite pool of threads. Previously, these oplock break jobs could end up taking all the running queues waiting for a page lock which blocks the callback required to free this page lock from being completed. This update separates the oplock break jobs into a separate workqueue VERY-SLOW-WORK, allowing the callbacks to be completed successfully and preventing the deadlock.
BZ#772317
Previously, network drivers that had Large Receive Offload (LRO) enabled by default caused the system to run slow, lose frame, and eventually prevent communication, when using software bridging. With this update, LRO is automatically disabled by the kernel on systems with a bridged configuration, thus preventing this bug.
BZ#772237
When transmitting a fragmented socket buffer (SKB), the qlge driver fills a descriptor with fragment addresses, after DMA-mapping them. On systems with pages larger than 8 KB and less than eight fragments per SKB, a macro defined the size of the OAL (Outbound Address List) list as 0. For SKBs with more than eight fragments, this would start overwriting the list of addresses already mapped and would make the driver fail to properly unmap the right addresses on architectures with pages larger than 8 KB. With this update, the size of external list for TX address descriptors have been fixed and qlge no longer fails in the described scenario.
BZ#772136
Prior to this update, the wrong size was being calculated for the vfinfo structure. Consequently, networking drivers that created a large number of virtual functions caused warning messages to appear when loading and unloading modules. Backported patches from upstream have been provided to resolve this issue, thus fixing this bug.
BZ#771251
The fcoe_transport_destroy path uses a work queue to destroy the specified FCoE interface. Previously, the destroy_work work queue item blocked another single-threaded work queue. Consequently, a deadlock between queues occurred and the system became unresponsive. With this update, fcoe_transport_destroy has been modified and is now a synchronous operation, allowing to break the deadlock dependency. As a result, destroy operations are now able to complete properly, thus fixing this bug.
BZ#786518
On a system that created and deleted lots of dynamic devices, the 31-bit Linux ifindex object failed to fit in the 16-bit macvtap minor range, resulting in unusable macvtap devices. The problem primarily occurred in a libvirt-controlled environment when many virtual machines were started or restarted, and caused libvirt to report the following message: Error starting domain: cannot open macvtap tap device /dev/tap222364: No such device or address With this update, the macvtap's minor device number allocation has been modified so that virtual machines can now be started and restarted as expected in the described scenario.
BZ#770023
A bug in the splice code has caused the file position on the write side of the sendfile() system call to be incorrectly set to the read side file position. This could result in the data being written to an incorrect offset. Now, sendfile() has been modified to correctly use the current file position for the write side file descriptor, thus fixing this bug.
Note that in the following common sendfile() scenarios, this bug does not occur: when both read and write file positions are identical and when the file position is not important (e.g. if the write side is a socket).
BZ#769626
Prior to this update, Active State Power Management (ASPM) was not properly disabled, and this interfered with the correct operation of the hpsa driver. Certain HP BIOS versions do not report a proper disable bit, and when the kernel fails to read this bit, the kernel defaults to enabling ASPM. Consequently, certain servers equipped with a HP Smart Array controller were unable to boot unless the pcie_aspm=off option was specified on the kernel command line. A backported patch has been provided to address this problem, ASPM is now properly disabled, and the system now boots up properly in the described scenario.
BZ#769590
Due to a race condition, running the "ifenslave -d bond0 eth0" command to remove the slave interface from the bonding device could cause the system to crash when a networking packet was being received at the same time. With this update, the race condition has been fixed and the system no longer crashes under these circumstances.
BZ#769007
In certain circumstances, the qla2xxx driver was unable to discover fibre channel (FC) tape devices because the ADISC ELS request failed. This update adds the new module parameter, ql2xasynclogin, to address this issue. When this parameter is set to "0", FC tape devices are discovered properly.
BZ#786960
When running AF_IUCV socket programs with IUCV transport, an IUCV SEVER call was missing in the callback of a receiving IUCV SEVER interrupt. Under certain circumstances, this could prevent z/VM from removing the corresponding IUCV-path completely. This update adds the IUCV SEVER call to the callback, thus fixing this bug. In addition, internal socket states have been merged, thus simplifying the AF_IUCV code.
BZ#767753
When the nohz=off kernel parameter was set, kernel could not enter any CPU C-state. With this update, the underlying code has been fixed and transitions to CPU idle states now work as expected.
BZ#766861
Under heavy memory and file system load, the "mapping->nrpages == 0" assertion could occur in the end_writeback() function. As a consequence, a kernel panic could occur. This update provides a reliable check for mapping->nrpages that prevent the described assertion, thus fixing this bug.
BZ#765720
An insufficiently designed calculation in the CPU accelerator in previous kernel caused an arithmetic overflow in the sched_clock() function when system uptime exceeded 208.5 days. This overflow led to a kernel panic on the systems using the Time Stamp Counter (TSC) or Virtual Machine Interface (VMI) clock source. This update corrects the aforementioned calculation so that this arithmetic overflow and kernel panic can no longer occur under these circumstances.
BZ#765673
Previously, the cfq_cic_link() function had a race condition. When some processes, which shared ioc issue I/O to the same block device simultaneously, cfq_cic_link() sometimes returned the -EEXIST error code. Consequently, one of the processes started to wait indefinitely. A patch has been provided to address this issue and the cfq_cic_lookup() call is now retried in the described scenario, thus fixing this bug.
BZ#667925
Previously, the SFQ qdisc packet scheduler class had no bind_tcf() method. Consequently, if a filter was added with the classid parameter to SFQ, a kernel panic occurred due to a null pointer dereference. With this update, the dummy ".unbind_tcf" and ".put" qdisc class options have been added to conform with the behaviour of other schedulers, thus fixing this bug.
BZ#787762
Previously, an incorrect portion of memory was freed when unmapping a DMA (Direct Memory Access) area used by the mlx4 driver. Consequently, a DMA leak occurred after removing a network device that used the driver. This update ensures that the mlx4 driver unmaps the correct portion of memory. As a result, the memory is freed correctly and no DMA leak occurs.
BZ#787771
Previously, when a memory allocation failure occurred, the mlx4 driver did not free the previously allocated memory correctly. Consequently, hotplug removal of devices using the mlx4 driver could not be performed. With this update, a memory allocation failure still occurs when the device MTU (Maximal Transfer Unit) is set to 9000, but hotplug removal the device is possible afer the failure.
BZ#759613
Due to a regression, the updated vmxnet3 driver used the ndo_set_features() method instead of various methods of the ethtool utility. Consequently, it was not possible to make changes to vmxnet3-based network adapters in Red Hat Enterprise Linux 6.2. This update restores the ability of the driver to properly set features, such as csum or TSO (TCP Segmentation Offload), via ethtool.
BZ#759318
Previously, when a MegaRAID 9265/9285 or 9360/9380 controller got a timeout in the megaraid_sas driver, the invalid SCp.ptr pointer could be called from the megasas_reset_timer() function. As a consequence, a kernel panic could occur. An upstream patch has been provided to address this issue and the pointer is now always set correctly.
BZ#790673
The vmxnet3 driver in Red Hat Enterprise Linux 6.2 introduced a regression. Due to an optimization, in which at least 54 bytes of a frame were copied to a contiguous buffer, shorter frames were dropped as the frame did not have 54 bytes available to copy. With this update, transfer size for a buffer is limited to 54 bytes or the frame size, whichever is smaller, and short frames are no longer dropped in the described scenario.
BZ#755885
Previously, when isolating pages for migration, the migration started at the start of a zone while the free scanner started at the end of the zone. Migration avoids entering a new zone by never going beyond what the free scanner scanned. In very rare cases, nodes overlapped and the migration isolated pages without the LRU lock held, which triggered errors in reclaim or during page freeing. With this update, the isolate_migratepages() function makes a check to ensure that it never isolates pages from a zone it does not hold the LRU lock for, thus fixing this bug.
BZ#755380
Due to regression, an attempt to open a directory that did not have a cached dentry failed and the EISDIR error code was returned. The same operation succeeded if a cached dentry existed. This update modifies the nfs_atomic_lookup() function to allow fallbacks to normal look-up in the described scenario.
BZ#754356
Due to a race condition, the mac80211 framework could deauthenticate with an access point (AP) while still scheduling authentication retries with the same AP. If such an authentication attempt timed out, a warning message was returned to kernel log files. With this update, when deauthenticating, pending authentication retry attempts are checked and cancelled if found, thus fixing this bug.
BZ#692767
Index allocation in the virtio-blk module was based on a monotonically increasing variable "index". Consequently, released indexes were not reused and after a period of time, no new ones were available. Now, virtio-blk uses the ida API to allocate indexes, thus preventing this bug.
BZ#795441
When expired user credentials were used in the RENEW() calls, the calls failed. Consequently, all access to the NFS share on the client became unresponsive. With this update, the machine credentials are used with these calls instead, thus preventing this bug most of the time. If no machine credentials are available, user credentials are used as before.
BZ#753301
Previously, an unnecessary assertion could trigger depending on the value of the xpt_pool field. As a consequence, a node could terminate unexpectedly. The xpt_pool field was in fact unnecessary and this update removes it from the sunrpc code, thus preventing this bug.
BZ#753237
Prior to this update, the align_va_addr kernel parameter was ignored if secondary CPUs were initialized. This happened because the parameter settings were overridden during the initialization of secondary CPUs. Also, the align_va_addr parameter documentation contained incorrect parameter arguments. With this update, the underlying code has been modified to prevent the overriding and the documentation has been updated. This update also removes the unused code introduced by the patch for BZ#739456.
BZ#796277
Concurrent look-up operations of the same inode that was not in the per-AG (Allocation Group) inode cache caused a race condition, triggering warning messages to be returned in the unlock_new_inode() function. Although this bug could only be exposed by NFS or the xfsdump utility, it could lead to inode corruption, inode list corruption, or other related problems. With this update, the XFS_INEW flag is set before inserting the inode into the radix tree. Now, any concurrent look-up operation finds the new inode with XFS_INEW set and the operation is then forced to wait until XFS_INEW is removed, thus fixing this bug.
BZ#753030
Socket callbacks use the svc_xprt_enqueue() function to add sockets to the pool->sp_sockets list. In normal operation, a server thread will later take the socket off that list. Previously, on the nfsd daemon shutdown, still-running svc_xprt_enqueue() could re-add an socket to the sp_sockets list just before it was deleted. Consequently, system could terminate unexpectedly by memory corruption in the sunrpc module. With this update, the XPT_BUSY flag is put on every socket and svc_xprt_enqueue() now checks this flag, thus preventing this bug.
BZ#816034
Red Hat Enterprise Virtualization Hypervisor became unresponsive and failed to shut down or restart with the following message:
Shutting down interface breth0
This happened after configuring the NetConsole functionality with no bridge on top of a bond due to a mistake in the linking to the device structure. With this update, the linking has been fixed and the device binding is processed correctly in this scenario.
BZ#752528
When the md_raid1_unplug_device() function was called while holding a spinlock, under certain device failure conditions, it was possible for the lock to be requested again, deeper in the call chain, and causing a deadlock. With this update, md_raid1_unplug_device() is no longer called while holding a spinlock, thus fixing this bug.
BZ#797731
Previously, a bonding device had always the UFO (UDP Fragmentation Offload) feature enabled even when no slave interfaces supported UFO. Consequently, the tracepath command could not return correct path MTU. With this update, UFO is no longer configured for bonding interfaces by default if the underlying hardware does not support it, thus fixing this bug.
BZ#703555
When trying to send a kdump file to a remote system via the tg3 driver, the tg3 NIC (network interface controller) could not establish the connection and the file could not be sent. The kdump kernel leaves the MSI-X interrupts enabled as set by the crashed kernel, however, the kdump kernel only enables one CPU and this could cause the interrupt delivery to the tg3 driver to fail. With this update, tg3 enables only a single MSI-X interrupt in the kdump kernel to match the overall environment, thus preventing this bug.
BZ#751087
On a system with an idle network interface card (NIC) controlled by the e1000e driver, when the card transmitted up to four descriptors, which delayed the write-back and nothing else, the run of the watchdog driver about two seconds later forced a check for a transmit hang in the hardware, which found the old entry in the TX ring. Consequently, a false "Detected Hardware Unit Hang" message was issued to the log. With this update, when the hang is detected, the descriptor is flushed and the hang check is run again, which fixes this bug.
BZ#750237
Previously, the idle_balance() function dropped or retook the rq->lock parameter, leaving the previous task vulnerable to the set_tsk_need_resched() function. Now, the parameter is cleared in setup_thread_stack() after a return from balancing and no successfully descheduled or never scheduled task has it set, thus fixing this bug.
BZ#750166
Previously, the doorbell register was being unconditionally swapped. If the Blue Frame option was enabled, the register was incorrectly written to the descriptor in the little endian format. Consequently, certain adapters could not communicate over a configured IP address. With this update, the doorbell register is not swapped unconditionally, rather, it is always converted to big endian before it is written to the descriptor, thus fixing this bug.
BZ#705698
The CFQ (Completely Fair Queuing) scheduler does idling on sequential processes. With changes to the IOeventFD feature, traffic pattern at CFQ changed and CFQ considered everything a thread was doing sequential I/O operations. Consequently, CFQ did not allow preemption across threads in Qemu. This update increases the preemption threshold and the idling is now limited in the described scenario without the loss of throughput.
BZ#798984
When short audio periods were configured, the ALSA PCM midlevel code, shared by all sound cards, could cause audio glitches and other problems. This update adds a time check for double acknowledged interrupts and improves stability of the snd-aloop kernel module, thus fixing this bug.
BZ#748559
Previously, the utime and stime values in the /proc/<pid>/stat file of a multi-threaded process could wrongly decrease when one of its threads exited. A backported patch has been provided to maintain monotonicity of utime and stime in the described scenario, thus fixing this bug.
BZ#800555
During tests with active I/O on 256 LUNs (logical unit numbers) over FCoE, a large number SCSI mid layer error messages were returned. As a consequence, the system became unresponsive. This bug has been fixed by limiting the source of the error messages and the hangs no longer occur in the described scenario.
BZ#714902
Previously, the compaction code assumed that memory on all cluster nodes is aligned to the same page-block size when isolating a cluster node for migration. However, when running a cluster on IBM System x3850 X5 machines with two MAX 5 memory expansion drawers, memory is not properly aligned. Therefore, the isolate_migratepages() function could pass an invalid Page Frame Number (PFN) to the pfn_to_page() function, which resulted in a kernel panic. With this update, the compaction code has been modified so that the isolate_migratepages() function now calls the pfn_valid function to validate PFN when necessary, and the kernel no longer panics in this scenario described.
BZ#801730
The ctx->vif identifier is dereferenced in different parts of the iwlwifi code. When it was set to null before requesting hardware reset, the kernel could terminate unexpectedly. An upstream patch has been provided to address this issue and the crashes no longer occur in the described scenario.
BZ#717179
Previously, a CPU could service the idle load balancer kick request from another CPU, even without receiving the IPI. Consequently, multiple __smp_call_function_single() calls were done on the same call_single_data structure, leading to a deadlock. To kick a CPU, the scheduler already has the reschedule vector reserved. Now, the kick_process mechanism is used instead of using the generic smp_call_function mechanism to kick off the nohz idle load balancing and avoid the deadlock.
BZ#746484
A software bug related to Context Caching existed in the Intel IOMMU support module. On some newer Intel systems, the Context Cache mode has changed from previous hardware versions, potentially exposing a Context coherency race. The bug was exposed when performing a series of hot plug and unplug operations of a Virtual Function network device which was immediately configured into the network stack, i.e., successfully performed dynamic host configuration protocol (DHCP). When the coherency race occurred, the assigned device would not work properly in the guest virtual machine. With this update, the Context coherency is corrected and the race and potentially resulting device assignment failure no longer occurs.
BZ#746169
Due to a running cursor blink timer, when attempting to hibernate certain types of laptops, the i915 kernel driver could corrupt memory. Consequently, the kernel could crash unexpectedly. An upstream patch has been provided to make the i915 kernel driver use the correct console suspend API and the hibernate function now works as expected.
BZ#720611
Previously, the eth_type_trans() function was called with the VLAN device type set. If a VLAN device contained a MAC address different from the original device, an incorrect packet type was assigned to the host. Consequently, if the VLAN devices were set up on a bonding interface in Adaptive Load Balancing (ALB) mode, the TCP connection could not be established. With this update, the eth_type_trans() function is called with the original device, ensuring that the connection is established as expected.
BZ#806081
The slave member of "struct aggregator" does not necessarily point to a slave which is part of the aggregator. It points to the slave structure containing the aggregator structure, while completely different slaves (or no slaves at all) may be part of the aggregator. Due to a regression, the agg_device_up() function wrongly used agg->slave to find the state of the aggregator. Consequently, wrong active aggregator was reported to the /proc/net/bonding/bond0 file. With this update, agg->lag_ports->slave is used in the described scenario instead, thus fixing this bug.
BZ#806119
Due to the netdevice handler for FCoE (Fibre Channel over Ethernet) and the exit path blocking the keventd work queue, the destroy operation on an NPIV (N_Port ID Virtualization) FCoE port led to a deadlock interdependency and caused the system to become unresponsive. With this update, the destroy_work item has been moved to its own work queue and is now executed in the context of the user space process requesting the destroy, thus preventing this bug.
BZ#739811
Previously, when pages were being migrated via NFS with an active requests on them, if a particular inode ended up deleted, then the VFS called the truncate_inode_pages() function. That function tried to take the page lock, but it was already locked when migrate_page() was called. As a consequence, a deadlock occurred in the code. This bug has been fixed and the migration request is now refused if the PagePrivate parameter is already set, indicating that the page is already associated with an active read or write request.
BZ#808487
Previously, requests for large data blocks with the ZSECSENDCPRB ioctl() system call failed due to an invalid parameter. A misleading error code was returned, concealing the real problem. With this update, the parameter for the ZSECSENDCPRB request code constant is validated with the correct maximum value. Now, if the parameter length is not valid, the EINVAL error code is returned, thus fixing this bug.
BZ#809928
Due to incorrect use of the list_for_each_entry_safe() macro, the enumeration of remote procedure calls (RPCs) priority wait queue tasks stored in the tk_wait.links list failed. As a consequence, the rpc_wake_up() and rpc_wake_up_status() functions failed to wake up all tasks. This caused the system to become unresponsive and could significantly decrease system performance. Now, the list_for_each_entry_safe() macro is no longer used in rpc_wake_up(), ensuring reasonable system performance.
BZ#812259
Various problems were discovered in the iwlwifi driver happening in the 5 GHz band. Consequently, roaming between access points (AP) on 2.4 GHz and 5 GHz did not work properly. This update adds a new option to the driver that disables the 5 GHz band support.
BZ#810299
Previously, secondary, tertiary, and other IP addresses added to bond interfaces could overwrite the bond->master_ip and vlan_ip values. Consequently, a wrong IP address could be occasionally used, the MII (Media Independent Interface) status of the backup slave interface went down, and the bonding master interfaces were switching. This update removes the master_ip and vlan_ip elements from the bonding and vlan_entry structures, respectively. Instead, devices are directly queried for the optimal source IP address for ARP requests, thus fixing this bug.
BZ#727700
An anomaly in the memory map created by the mbind() function caused a segmentation fault in Hotspot Java Virtual Machines with the NUMA-aware Parallel Scavenge garbage collector. A backported upstream patch that fixes mbind() has been provided and the crashes no longer occur in the described scenario.
BZ#812108
Previously, with a transparent proxy configured and under high load, the kernel could start to drop packets, return error messages such as "ip_rt_bug: addr1 -> addr2, ?", and, under rare circumstances, terminate unexpectedly. This update provides patches addressing these issues and the described problems no longer occur.
BZ#811815
The kdump utility does not support Xen para-virtualized (PV) drivers on Hardware Virtualized Machine (HVM) guests in Red Hat Enterprise Linux 6. Therefore, kdump failed to start if the guest had loaded PV drivers. This update modifies underlying code to allow kdump to start without PV drivers on HVM guests configured with PV drivers.
BZ#735105
When running a userspace program, such as the Ceph client, on the ext4 file system, a race condition between the sync/flush thread and the xattr-set thread could occur. This was caused by an incorrectly-set state flag on an inode. As a consequence, memory for the file system was incorrectly allocated, which resulted in file system corruption. With this update, the ext4 code has been modified to prevent this race condition from occurring and file systems are no longer corrupted under these circumstances.
BZ#728852
An unwanted interrupt was generated when a PCI driver switched the interrupt mechanism from the Message Signaled Interrupt (MSI or MSI-X) to the INTx emulation while shutting down a device. Due to this, an interrupt handler was called repeatedly, and the system became unresponsive. On certain systems, the interrupt handler of Intelligent Platform Management Interface (IPMI) was called while shutting down a device on the way to reboot the system after running kdump. In such a case, soft lockups were performed repeatedly and the shutdown process never finished. With this update, the user can choose not to use MSI or MSI-X for the PCI Express Native Hotplug driver. The switching between the interrupt mechanisms is no longer performed so that the unwanted interrupt is not generated.
BZ#731917
The time-out period in the qla2x00_fw_ready() function was hard-coded to 20 seconds. This period was too short for new QLogic host bus adapters (HBAs) for Fibre Channel over Ethernet (FCoE). Consequently, some logical unit numbers (LUNs) were missing after a reboot. With this update, the time-out period has been set to 60 seconds so that the modprobe utility is able to recheck the driver module, thus fixing this bug.
BZ#730045
Previously, the idmapper utility pre-allocated space for all user and group names on an NFS client in advance. Consequently, page allocation failure could occur, preventing a proper mount of a directory. With this update, the allocation of the names is done dynamically when needed, the size of the allocation table is now greatly reduced, and the allocation failures no longer occur.
BZ#811703
As part of mapping the application's memory, a buffer to hold page pointers is allocated and the count of mapped pages is stored in the do_dio field. A non-zero do_dio marks that direct I/O is in use. However, do_dio is only one byte in size. Previously, mapping 256 pages overflowed do_dio and caused it to be set to 0. As a consequence, when large enough number of read or write requests were sent using the st driver's direct I/O path, a memory leak could occur in the driver. This update increases the size of do_dio, thus preventing this bug.
BZ#728315
In the hpet_next_event() function, an interrupt could have occurred between the read and write of the HPET (High Performance Event Timer) and the value of HPET_COUNTER was then beyond that being written to the comparator (HPET_Tn_CMP). Consequently, the timers were overdue for up to several minutes. Now, a comparison is performed between the value of the counter and the comparator in the HPET code. If the counter is beyond the comparator, the "-ETIME" error code is returned, which fixes this bug.
BZ#722297
In a Boot-from-San (BFS) installation via certain iSCSI adapters, driver exported sendtarget entries in the sysfs file system but the iscsistart failed to perform discovery. Consequently, a kernel panic occurred during the first boot sequence. With this update, the driver performs the discovery instead, thus preventing this bug.
BZ#805519
The SCSI layer was not using a large enough buffer to properly read the entire 'BLOCK LIMITS VPD' page that is advertised by a storage array. Consequently, the 'WRITE SAME MAX LEN' parameter was read incorrectly and this could result in the block layer issuing discard requests that were too large for the storage array to handle. This update increases the size of the buffer that the 'BLOCK LIMITS VPD' page is read into and the discard requests are now issued with proper size, thus fixing this bug.
BZ#803378
The Intelligent Platform Management Interface (IPMI) specification requires a minimum communication timeout of five seconds. Previously, the kernel incorrectly used a timeout of 1 second. This could result in failures to communicate with Baseboard Management Controllers (BMC) under certain circumstances. With this update, the timeout has been increased to five seconds to prevent such problems.
BZ#758404
The dm_mirror module can send discard requests. However, the dm_io interface did not support discard requests, and running an LVM mirror over a discard-enabled device led to a kernel panic. This update adds support for the discard requests to the dm_io interface, so that kernel panics no longer occur in the described scenario.
BZ#766051
Previously, when the schedule() function was run shortly after a boot, the following warning message was sometimes returned once per boot on the console:
5915: WARN_ON_ONCE(test_tsk_need_resched(next));
An upstream patch has been provided to address this issue and the WARN_ON_ONCE() call is no longer present in schedule(), thus fixing this bug.
BZ#786996
Prior to this update, bugs in the close() and send() functions caused delays and operation of these two functions took too long to complete. This update adds the IUCV_CLOSED state change and improves locking for close(). Also, the net_device handling has been improved in send(). As a result, the delays no longer occur.
BZ#770250
On NFS, when repeatedly reading a directory, content of which kept changing, the client issued the same readdir request twice. Consequently, the following warning messages were returned to the dmesg output:
NFS: directory A/B/C contains a readdir loop.
This update fixes the bug by turning off the loop detection and letting the NFS client try to recover in the described scenario and the messages are no longer returned.
BZ#635817
A number of patches have been applied to the kernel in Red Hat Enterprise Linux 6.3 to improve overall performance and reduce boot time on extremely large UV systems (patches were tested on a system with 2048 cores and 16 TB of memory). Additionally, boot messages for the SGI UV2 platform were updated.
BZ#822697
Previously, if creation of an MFN (Machine Frame Number) was lazily deferred, the MFN could appear invalid when is was not. If at this point read_pmd_atomic() was called, which then called the paravirtualized __pmd() function, and returned zero, the kernel could terminate unexpectedly. With this update, the __pmd() call is avoided in the described scenario and the open-coded compound literal is returned instead, thus fixing this bug.
BZ#781566
Previously, on a system where intermediate P-states were disabled, the powernow-k8 driver could cause a kernel panic in the cpufreq subsystem. Additionally, not all available P-states were recognized by the driver. This update modifies the drive code so that it now properly recognizes all P-states and does not cause the panics in the described scenario.
BZ#783497
Due to an off-by-one bug in max_blocks checks, on the 64-bit PowerPC architecture, the tmpfs file system did not respect the size= parameter and consequently reported incorrect number of available blocks. A backported upstream patch has been provided to address this issue and tmpfs now respects the size= parameter as expected.
BZ#681906
This update introduces a performance enhancement which dramatically improves the time taken to read large directories from disk when accessing them sequentially. Large in this case means several hundred thousand entries or more. It does not affect the speed of looking up individual files (which is already fast), nor does it make any noticeable difference for smaller directories. Once a directory is cached, then again no difference can be noticed in performance. The initial read however, should be faster due to the readahead which this update introduces.
BZ#729586
Red Hat Enterprise Linux 6.1 introduced naming scheme adjustments for emulated SCSI disks used with paravirtual drivers to prevent namespace clashes between emulated IDE and emulated SCSI disks. Both emulated disk types use the paravirt block device xvd. Consider the example below:

Table 5.1. The naming scheme example

Red Hat Enterprise Linux 6.0 Red Hat Enterprise Linux 6.1 or later
emulated IDE hda -> xvda unchanged
emulated SCSI sda -> xvda sda -> xvde, sdb -> xvdf, ...

This update introduces a new module parameter, xen_blkfront.sda_is_xvda, that provides a seamless upgrade path from 6.0 to 6.3 kernel release. The default value of xen_blkfront.sda_is_xvda is 0 and it keeps the naming scheme consistent with 6.1 and later releases. When xen_blkfront.sda_is_xvda is set to 1, the naming scheme reverts to the 6.0-compatible mode.

Note

Note that when upgrading from 6.0 to 6.3 release, if a virtual machine specifies emulated SCSI devices and utilizes paravirtual drivers and uses explicit disk names such as xvd[a-d], it is advised to add the xen_blkfront.sda_is_xvda=1 parameter to the kernel command line before performing the upgrade.
BZ#756307
In previous Red Hat Enterprise Linux 6 releases, the kernel option xen_emul_unplug=never did not disable xen platform pci device and that lead to using para-virtual devices instead of emulated ones. This fix, in addition to fixing the irq allocation issue for emulated network devices, allows to disable para-virtual drivers using the xen_emul_unplug=never kernel option as described in "Virtualization Guide: Edition 5.8" chapter "12.3.5. Xen Para-virtualized Drivers on Red Hat Enterprise Linux 6".
BZ#749251
When a process isolation mechanism such as LXC (Linux Containers) was used and the user space was running without the CAP_SYS_ADMIN identifier set, a jailed root user could bypass the dmesg_restrict protection, creating an inconsistency. Now, writing to dmesg_restrict is only allowed when the root has CAP_SYS_ADMIN set, thus preventing this bug.
BZ#788591
Previously, the code for loading multipath tables attempted to load the scsi_dh module even when it was already loaded, which caused the system to become unresponsive. With this update, the code does not attempt to load the scsi_dh module when it is already loaded and multipath tables are loaded successfully.
BZ#801877
Due to an error in the code for ASPM (Active State Power Management) tracking, the system terminated unexpectedly after attempts to remove a PCI bus with both PCIe and PCI devices connected to it when PCIe ASPM was disabled using the "pcie_aspm=off" kernel parameter. This update ensures that the ASPM handling code is not executed when ASPM is disabled and the server no longer crashes in the aforementioned scenario.
BZ#804608
Due to an error in the underlying source code, the perf performance counter subsystem calculated event frequencies incorrectly. This update fixes the code and calculation of event frequencies now returns correct results.
BZ#787771
Previously, when a memory allocation failure occurred, the mlx4 driver did not free the previously allocated memory correctly. Consequently, hotplug removal of devices using the mlx4 driver could not be performed. With this update, a memory allocation failure still occurs when the device MTU (Maximal Transfer Unit) is set to 9000, but hotplug removal the device is possible afer the failure.
BZ#787762
Previously, an incorrect portion of memory was freed when unmapping a DMA (Direct Memory Access) area used by the mlx4 driver. Consequently, a DMA leak occurred after removing a network device that used the driver. This update ensures that the mlx4 driver unmaps the correct portion of memory. As a result, the memory is freed correctly and no DMA leak occurs.
BZ#812415
The Intel SCU driver did not properly interact with the system BIOS to honor the Spread Spectrum Clock (SSC) settings and state by the BIOS controls: even though the SSC mode was enabled in the preboot BIOS environment, it became disabled after boot due to incorrect parameter parsing from the ROM option. With this update, the kernel driver has been modified to correctly parse OEM parameters from the ROM option and the problem no longer occurs.
BZ#811023
The iw_cxgb4 driver has been updated so as to fix a race that occurred when an ingress abort failed to wake up the thread blocked in rdma_init() causing the application to become unresponsive. Also, the driver has been modified to return and not to call the wake_up() function if no endpoint is found as this is not necessary.
BZ#818371
When creating a snapshot of a mounted RAID volume, a kernel panic could occur. This happened because a timer designed to wake up an I/O processing thread was not deactivated when the RAID device was replace by a snapshot origin. The timer then woke a thread that attempted to access memory that had already been freed, resulting in a kernel panic. With this update, this bug has been fixed and the kernel panic no longer occurs in this scenario.
BZ#821329
Previously, attempts to add a write-intent bitmap to an MD array using v1.0 metadata and then using the array without rebooting caused a kernel OOPS. This occurred because the kernel did not reload the bitmap information correctly after creating the bitmap. With this update, the kernel loads the information correctly on bitmap creation, as expected and the kernel OOPS no longer occurs.
BZ#817090
On IBM System z, a kernel panic could occur if there was high traffic workload on HiperSockets devices. This happened due to a conflict in the qeth driver between asynchronous delivery of storage blocks for HiperSockets devices and outdated SIGA (System Information GAthering) retry code. With this update, the SIGA retry code has been removed from the qeth driver and the problem no longer occurs.
BZ#736931
Previously, certain internal functions in the real-time scheduler only iterated over runnable real-time tasks instead of iterating over all existing tasks. Consequently, when processing multiple real-time threads on multiple logical CPUs and one CPU was disabled, the kernel could panic with the following error message:
kernel BUG at kernel/sched_rt.c:460!
This update modifies the real-time scheduler so that all real-time tasks are processed as expected and the kernel no longer crashes in this scenario.
BZ#756301
Due to a bug in the qla2xxx driver and the HBA firmware, storage I/O traffic could become unresponsive during storage fault testing. With this update, these bugs have been fixed and storage traffic no longer hangs in the described scenario.
BZ#767505
When resetting a virtual block device and a config interrupt was received, the config_work handler could attempt to access the device configuration after the device had already been removed from the system but before the device was reset. This resulted in a kernel panic. With this update, the underlying code has been modified to use a mutex lock and disable the device configuration during the reset. Config interrupts can no longer be processed during the reset of the virtual block device and the kernel no longer panics in this scenario.
BZ#784430
After some recent changes in USB driver code, previous versions of the kernel did not handle, under some circumstances, standard and warm reset of USB3.0 ports correctly. Consequently, the system was not able to detect and automatically mount a USB3.0 device when the device was re-attached to a USB3.0 port after it was unmounted. This update applies several upstream patches related to handling USB3.0 ports, and USB3.0 devices are now automatically re-attached as expected in the scenario described.
BZ#738491
Previously, the mlx4 driver expected Remote Direct Memory Access (RDMA) communication to be performed over an InfiniBand link layer and the driver thus used the InfiniBand link layer part of the code to record transfer statistics. However, Mellanox RDMA over Converged Ethernet (RoCE) devices use an Ethernet link layer for RDMA communication, which caused that RDMA communication was not accounted under these circumstances, and the displayed statistics were incorrect. With this update, the underlying code has been modified so that the driver now uses a "global" counter for RDMA traffic accounting on Ethernet ports, and users can see correct RDMA transfer statistics.
BZ#749059
Due to a missing validation check, the mlx4 driver could attempt to access an already freed data element in the core network device structure of the network layer. As a consequence, if a Mellanox ConnectX HCA InfiniBand adapter was unexpectedly removed from the system while the adapter processed ongoing Remote Direct Memory Access (RDMA) communication, the kernel panicked. With this update, the mlx4 driver has been modified to verify that the core network device structure is valid before attempting to use it for outgoing communication. The kernel now no longer panics when an adapter port is unexpectedly disabled.

Enhancements

Note

For more information on the most important of the RHEL 6.3 kernel enhancements, refer to the Kernel and Device Drivers chapters in the Red Hat Enterprise Linux 6.3 Release Notes.
For a summary of added or updated procfs entries, sysfs default values, boot parameters, kernel configuration options, or any noticeable behavior changes, refer to Chapter 1, Important Changes to External Kernel Parameters.
BZ#808315
LED support has been added to the sysfs interfaces.
BZ#805658
The WinFast VP200 H (Teradici) snd-hda-intel audio device has been added, and is recognized by the alsa driver.
BZ#744301
The Brocade BFA Fibre Channel and FCoE driver is no longer a Technology Preview. In Red Hat Enterprise Linux 6.3 the BFA driver is fully supported.
BZ#744302
The Brocade BNA driver for Brocade 10Gb PCIe ethernet Controllers is no longer a Technology Preview. In Red Hat Enterprise Linux 6.3 the BNA driver is fully supported.
BZ#696383
Persistent storage (pstore), a file system interface for platform dependent persistent storage, now supports UEFI.
BZ#661765
This release adds support for a new kernel auditing feature that allows for inter-field comparisons. For each audit event, the kernel collects information about what is causing the event. Now, you can use the "-C" command to tell the kernel to compare: auid, uid, euid, suid, fsuid, or obj_uid; and gid, egid, sgid, fsgid, or obj_gid. The two groups cannot be mixed. Comparisons can use either of the equal or not equal operators.
BZ#821561
This update adds the rh_check_unsupported() function and blacklists unsupported future Intel processors.
BZ#786997
When AF_IUCV sockets were using the HiperSockets transport, maximum message size for such transports depended on the MTU (maximum transmission unit) size of the HiperSockets device bound to a AF_IUCV socket. However, a socket program could not determine maximum size of a message. This update adds the MSGSIZE option for the getsockopt() function. Through this option, the maximum message size can be read and properly handled by AF_IUCV.
BZ#596419
The cred argument has been included in the security_capable() function so that it can be used in a wider range of call sites.
BZ#773052
Red Hat Enterprise Linux 6.3 adds support for the Wacom Cintiq 24HD (a 24-inch Drawing Tablet).
BZ#738720
This update adds additional fixed tracepoints to trace signal events.
BZ#704003
This update adds the missing raid6test.ko module.
BZ#788634
The keyrings kernel facility has been upgraded to the upstream version, which provides a number of bug fixes and enhancements over the previous version. In particular, the garbage collection mechanism has been re-worked.
BZ#788156
The perf tool has been upgraded to upstream version 3.3-rc1, which provides a number of bug fixes and enhancements over the previous version.
BZ#766952
The wireless LAN subsystem has been updated. It introduces the dma_unmap state API and adds a new kernel header file: include/linux/pci-dma.h.
BZ#723018
The dm-thinp targets, thin and thin-pool, provide a device mapper device with thin-provisioning and scalable snapshot capabilities. This feature is available as a Technology Preview.
BZ#768460
In Red Hat Enterprise Linux 6.3, SHA384 and SHA512 HMAC authentication algorithms have been added to XFRM.
Users should upgrade to these updated packages, which contain backported patches to correct these issues, fix these bugs, and add these enhancement. The system must be rebooted for this update to take effect.
Updated kernel packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 6.3 Extended Update Support.
The Red Hat Security Response Team has rated this update as having important security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link associated with the description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix

CVE-2013-0871, Important
This update fixes the following security issue:
* A race condition was found in the way the Linux kernel's ptrace implementation handled PTRACE_SETREGS requests when the debuggee was woken due to a SIGKILL signal instead of being stopped. A local, unprivileged user could use this flaw to escalate their privileges.

Bug Fixes

BZ#908735
Previously, init scripts were unable to set the MAC address of the master interface properly because it was overwritten by the first slave MAC address. To avoid this problem, this update re-introduces the check for an unassigned MAC address before setting the MAC address of the first slave interface as the MAC address of the master interface.
BZ#909158
When using transparent proxy (TProxy) over IPv6, the kernel previously created neighbor entries for local interfaces and peers that were not reachable directly. This update corrects this problem and the kernel no longer creates invalid neighbor entries.
BZ#915582
Due to the incorrect validation of a pointer dereference in the d_validate() function, running a command such as ls or find on the MultiVersion File System (MVFS), used by IBM Rational ClearCase, for example, could trigger a kernel panic. This update modifies d_validate() to verify the parent-child dentry relationship by searching through the parent's d_child list. The kernel no longer panics in this situation.
BZ#916956
A previously backported patch introduced usage of the page_descs length field but did not set the page data length for the FUSE page descriptor. This code path can be exercised by a loopback device (pagecache_write_end) if used over FUSE. As a result, fuse_copy_page does not copy page data from the page descriptor to the user-space request buffer and the user space can see uninitialized data. This could previously lead to file system data corruption. This problem has been fixed by setting the page_descs length prior to submitting the requests, and FUSE therefore provides correctly initialized data.
Users should upgrade to these updated packages, which contain backported patches to resolve these issues. The system must be rebooted for this update to take effect.
Updated kernel packages that fix one security issue are now available for Red Hat Enterprise Linux 6.3 Extended Update Support.
The Red Hat Security Response Team has rated this update as having important security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link associated with the description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix

CVE-2013-2094, Important
This update fixes the following security issue:
* It was found that the Red Hat Enterprise Linux 6.1 kernel update (RHSA-2011:0542) introduced an integer conversion issue in the Linux kernel's Performance Events implementation. This led to a user-supplied index into the perf_swevent_enabled array not being validated properly, resulting in out-of-bounds kernel memory access. A local, unprivileged user could use this flaw to escalate their privileges.
A public exploit that affects Red Hat Enterprise Linux 6 is available.
Refer to Red Hat Knowledge Solution 373743, linked to in the References, for further information and mitigation instructions for users who are unable to immediately apply this update.
Users should upgrade to these updated packages, which contain a backported patch to correct this issue. The system must be rebooted for this update to take effect.
Updated kernel packages that fix three security issues and several bugs are now available for Red Hat Enterprise Linux 6.3 Extended Update Support.
The Red Hat Security Response Team has rated this update as having important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links associated with each description below.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fixes

CVE-2013-2224, Important
It was found that the fix for CVE-2012-3552 released via RHSA-2012:1540 introduced an invalid free flaw in the Linux kernel's TCP/IP protocol suite implementation. A local, unprivileged user could use this flaw to corrupt kernel memory via crafted sendmsg() calls, allowing them to cause a denial of service or, potentially, escalate their privileges on the system.
CVE-2013-4299, Moderate
An information leak flaw was found in the way Linux kernel's device mapper subsystem, under certain conditions, interpreted data written to snapshot block devices. An attacker could use this flaw to read data from disk blocks in free space, which are normally inaccessible.
CVE-2013-2852, Low
A format string flaw was found in the b43_do_request_fw() function in the Linux kernel's b43 driver implementation. A local user who is able to specify the "fwpostfix" b43 module parameter could use this flaw to cause a denial of service or, potentially, escalate their privileges.
Red Hat would like to thank Fujitsu for reporting CVE-2013-4299, and Kees Cook for reporting CVE-2013-2852.

Bug Fixes

BZ#1004185
An insufficiently designed calculation in the CPU accelerator could cause an arithmetic overflow in the set_cyc2ns_scale() function if the system uptime exceeded 208 days prior to using kexec to boot into a new kernel. This overflow led to a kernel panic on the systems using the Time Stamp Counter (TSC) clock source, primarily the systems using Intel Xeon E5 processors that do not reset TSC on soft power cycles. A patch has been applied to modify the calculation so that this arithmetic overflow and kernel panic can no longer occur under these circumstances.
BZ#1007467
A race condition in the abort task and SPP device task management path of the isci driver could, under certain circumstances, cause the driver to fail cleaning up timed-out I/O requests that were pending on an SAS disk device. As a consequence, the kernel removed such a device from the system. A patch applied to the isci driver fixes this problem by sending the task management function request to the SAS drive anytime the abort function is entered and the task has not completed. The driver now cleans up timed-out I/O requests as expected in this situation.
BZ#1008507
A kernel panic could occur during path failover on systems using multiple iSCSI, FC or SRP paths to connect an iSCSI initiator and an iSCSI target. This happened because a race condition in the SCSI driver allowed removing a SCSI device from the system before processing its run queue, which led to a NULL pointer dereference. The SCSI driver has been modified and the race is now avoided by holding a reference to a SCSI device run queue while it is active.
All kernel users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.
Updated kernel packages that fix several bugs are now available for Red Hat Enterprise Linux 6 Extended Update Support.
The kernel packages contain the Linux kernel, the core of any Linux operating system.

Bug Fixes

BZ#979291
Cyclic adding and removing of the st kernel module could previously cause a system to become unresponsive. This was caused by a disk queue reference count bug in the SCSI tape driver. An upstream patch addressing this bug has been backported to the SCSI tape driver and the system now responds as expected in this situation.
BZ#982114
The bnx2x driver could have previously reported an occasional MDC/MDIO timeout error along with the loss of the link connection. This could happen in environments using an older boot code because the MDIO clock was set in the beginning of each boot code sequence instead of per CL45 command. To avoid this problem, the bnx2x driver now sets the MDIO clock per CL45 command. Additionally, the MDIO clock is now implemented per EMAC register instead of per port number, which prevents ports from using different EMAC addresses for different PHY accesses. Also, boot code or Management Firmware (MFW) upgrade is required to prevent the boot code (firmware) from taking over link ownership if the driver's pulse is delayed. The BCM57711 card requires boot code version 6.2.24 or later, and the BCM57712/578xx cards require MFW version 7.4.22 or later.
BZ#982469
If the audit queue is too long, the kernel schedules the kauditd daemon to alleviate the load on the audit queue. Previously, if the current audit process had any pending signals in such a situation, it entered a busy-wait loop for the duration of an audit backlog timeout because the wait_for_auditd() function was called as an interruptible task. This could lead to system lockup in non-preemptive uniprocessor systems. This update fixes the problem by setting wait_for_auditd() as uninterruptible.
BZ#988226
The kernel could rarely terminate instead of creating a dump file when a multi-threaded process using FPU aborted. This happened because the kernel did not wait until all threads became inactive and attempted to dump the FPU state of active threads into memory which triggered a BUG_ON() routine. A patch addressing this problem has been applied and the kernel now waits for the threads to become inactive before dumping their FPU state into memory.
BZ#990087
BE family hardware could falsely indicate an unrecoverable error (UE) on certain platforms and stop further access to be2net-based network interface cards (NICs). A patch has been applied to disable the code that stops further access to hardware for BE family network interface cards (NICs). For a real UE, it is not necessary as the corresponding hardware block is not accessible in this situation.
BZ#991344
The fnic driver previously allowed I/O requests with the number of SGL descriptors greater than is supported by Cisco UCS Palo adapters. Consequently, the adapter returned any I/O request with more than 256 SGL descriptors with an error indicating invalid SGLs. A patch has been applied to limit the maximum number of supported SGLs in the fnic driver to 256 and the problem no longer occurs.
Users should upgrade to these updated packages, which contain backported patches to correct these bugs. The system must be rebooted for this update to take effect