Synopsis

Moderate: kernel security and bug fix update

Type/Severity

Security Advisory: Moderate

Topic

An update for kernel is now available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having a security impact of Moderate. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es):

• When creating audit records for parameters to executed children processes, an attacker can convince the Linux kernel audit subsystem can create corrupt records which may allow an attacker to misrepresent or evade logging of executing commands. (CVE-2016-6136, Moderate)
• A flaw was found in the Linux kernel's implementation of the SCTP protocol. A remote attacker could trigger an out-of-bounds read with an offset of up to 64kB potentially causing the system to crash. (CVE-2016-9555, Moderate)

Bug Fix(es):

• The qlnic driver previously attempted to fetch pending transmission descriptors before all writes were complete, which lead to firmware hangs. With this update, the qlcnic driver has been fixed to complete all writes before the hardware fetches any pending transmission descriptors. As a result, the firmware no longer hangs with the qlcnic driver. (BZ#1403143)
• Previously, when a NFS share was mounted, the file-system (FS) cache was incorrectly enabled even when the "-o fsc" option was not used in the mount command. Consequently, the cachefilesd service stored files in the NFS share even when not instructed to by the user. With this update, NFS does not use the FS cache if not instructed by the "-o fsc" option. As a result, NFS no longer enables caching if the "-o fsc" option is not used. (BZ#1399172)
• Previously, an NFS client and NFS server got into a NFS4 protocol loop involving a WRITE action and a NFS4ERR_EXPIRED response when the current_fileid counter got to the wraparound point by overflowing the value of 32 bits. This update fixes the NFS server to handle the current_fileid wraparound. As a result, the described NFS4 protocol loop no longer occurs. (BZ#1399174)
• Previously, certain configurations of the Hewlett Packard Smart Array (HPSA) devices caused hardware to be set offline incorrectly when the HPSA driver was expected to wait for existing I/O operations to complete. Consequently, a kernel panic occurred. This update prevents the described problem. As a result, the kernel panic no longer occurs. (BZ#1399175)
• Previously, memory corruption by copying data into the wrong memory locations sometimes occurred, because the __copy_tofrom_user() function was returning incorrect values. This update fixes the __copy_tofrom_user() function so that it no longer returns larger values than the number of bytes it was asked to copy. As a result, memory corruption no longer occurs in he described scenario. (BZ#1398185)
• Previously, guest virtual machines (VMs) on a Hyper-V server cluster got in some cases rebooted during the graceful node failover test, because the host kept sending heartbeat packets independently of guests responding to them. This update fixes the bug by properly responding to all the heartbeat messages in the queue, even if they are pending. As a result, guest VMs no longer get rebooted under the described circumstances. (BZ#1397739)
• When the "punching hole" feature of the fallocate utility was used on an ext4 file system inode with extent depth of 1, the extent tree of the inode sometimes became corrupted. With this update, the underlying source code has been fixed, and extent tree corruption no longer occurs in the described situation. (BZ#1397808)

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 1353533 - CVE-2016-6136 kernel: Race condition vulnerability in execve argv arguments
• BZ - 1397930 - CVE-2016-9555 kernel: Slab out-of-bounds access in sctp_sf_ootb()

CVEs

• CVE-2016-6136
• CVE-2016-9555

References