RHSA-2015:1139 - Security Advisory

Topic

Updated kernel-rt packages that fix multiple security issues, several bugs,
and add various enhancements are now available for Red Hat Enterprise
Linux 7.

Red Hat Product Security 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 in the References section.

Description

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

• It was found that the Linux kernel's implementation of vectored pipe read

and write functionality did not take into account the I/O vectors that were
already processed when retrying after a failed atomic access operation,
potentially resulting in memory corruption due to an I/O vector array
overrun. A local, unprivileged user could use this flaw to crash the system
or, potentially, escalate their privileges on the system. (CVE-2015-1805,
Important)

• A race condition flaw was found in the way the Linux kernel keys

management subsystem performed key garbage collection. A local attacker
could attempt accessing a key while it was being garbage collected, which
would cause the system to crash. (CVE-2014-9529, Moderate)

• A flaw was found in the way the Linux kernel's 32-bit emulation

implementation handled forking or closing of a task with an 'int80' entry.
A local user could potentially use this flaw to escalate their privileges
on the system. (CVE-2015-2830, Low)

• It was found that the Linux kernel's ISO file system implementation did

not correctly limit the traversal of Rock Ridge extension Continuation
Entries (CE). An attacker with physical access to the system could use this
flaw to trigger an infinite loop in the kernel, resulting in a denial of
service. (CVE-2014-9420, Low)

• An information leak flaw was found in the way the Linux kernel's ISO9660

file system implementation accessed data on an ISO9660 image with RockRidge
Extension Reference (ER) records. An attacker with physical access to the
system could use this flaw to disclose up to 255 bytes of kernel memory.
(CVE-2014-9584, Low)

• A flaw was found in the way the nft_flush_table() function of the Linux

kernel's netfilter tables implementation flushed rules that were
referencing deleted chains. A local user who has the CAP_NET_ADMIN
capability could use this flaw to crash the system. (CVE-2015-1573, Low)

• An integer overflow flaw was found in the way the Linux kernel randomized

the stack for processes on certain 64-bit architecture systems, such as
x86-64, causing the stack entropy to be reduced by four. (CVE-2015-1593,
Low)

Red Hat would like to thank Carl Henrik Lunde for reporting CVE-2014-9420
and CVE-2014-9584. The security impact of CVE-2015-1805 was discovered by
Red Hat.

The kernel-rt packages have been upgraded to version 3.10.0-229.7.2, which
provides a number of bug fixes and enhancements over the previous version,
including:

• storvsc: get rid of overly verbose warning messages
• storvsc: force discovery of LUNs that may have been removed
• storvsc: in responce to a scan event, scan the hos
• storvsc: NULL pointer dereference fix
• futex: Mention key referencing differences between shared and private

futexes

• futex: Ensure get_futex_key_refs() always implies a barrier
• kernel module: set nx before marking module MODULE_STATE_COMING
• kernel module: Clean up ro/nx after early module load failures
• btrfs: make xattr replace operations atomic
• megaraid_sas: revert: Add release date and update driver version
• radeon: fix kernel segfault in hwmonitor

(BZ#1223955)

Bug fix:

• There is an XFS optimization that depended on a spinlock to disable

preemption using the preempt_disable() function. When CONFIG_PREEMPT_RT is
enabled on realtime kernels, spinlocks do not disable preemption while
held, so the XFS critical section was not protected from preemption.
Systems on the Realtime kernel-rt could lock up in this XFS optimization
when a task that locked all the counters was then preempted by a realtime
task, causing all callers of that lock to block indefinitely. This update
disables the optimization when building a kernel with
CONFIG_PREEMPT_RT_FULL enabled. (BZ#1223955)

All kernel-rt users are advised to upgrade to these updated packages, which
correct these issues and add these enhancements. The system must be
rebooted for this update to take effect.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

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

Affected Products

• Red Hat Enterprise Linux for Real Time 7 x86_64

Fixes

• BZ - 1175235 - CVE-2014-9420 Kernel: fs: isofs: infinite loop in CE record entries
• BZ - 1179813 - CVE-2014-9529 kernel: use-after-free during key garbage collection
• BZ - 1180119 - CVE-2014-9584 kernel: isofs: unchecked printing of ER records
• BZ - 1190966 - CVE-2015-1573 kernel: panic while flushing nftables rules that reference deleted chains.
• BZ - 1192519 - CVE-2015-1593 kernel: Linux stack ASLR implementation Integer overflow
• BZ - 1202855 - CVE-2015-1805 kernel: pipe: iovec overrun leading to memory corruption
• BZ - 1208598 - CVE-2015-2830 kernel: int80 fork from 64-bit tasks mishandling
• BZ - 1212083 - kernel-rt: rebase to the RHEL7.1.z batch3 source tree

CVEs

• CVE-2014-9420
• CVE-2014-9529
• CVE-2014-9584
• CVE-2015-1573
• CVE-2015-1593
• CVE-2015-1805
• CVE-2015-2830

References

• http://www.redhat.com/security/updates/classification/#normal