Issued:
2016-08-02
Updated:
2016-08-02

RHSA-2016:1541 - Important: kernel-rt security and bug fix update

Synopsis

Important: kernel-rt security and bug fix update

Type/Severity

Security Advisory Important

Topic

An update for kernel-rt is now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having a security impact of Important. 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-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements.

  • A flaw was found in the Linux kernel's keyring handling code, where in key_reject_and_link() an uninitialised variable would eventually lead to arbitrary free address which could allow attacker to use a use-after-free style attack. (CVE-2016-4470, Important)

  • The ovl_setattr function in fs/overlayfs/inode.c in the Linux kernel through 4.3.3 attempts to merge distinct setattr operations, which allows local users to bypass intended access restrictions and modify the attributes of arbitrary overlay files via a crafted application. (CVE-2015-8660, Moderate)

Red Hat would like to thank Nathan Williams for reporting CVE-2015-8660. The CVE-2016-4470 issue was discovered by David Howells (Red Hat Inc.).

The kernel-rt packages have been upgraded to the kernel-3.10.0-327.28.2.el7 source tree, which provides a number of bug fixes over the previous version. (BZ#1350307)

This update also fixes the following bugs:

  • Previously, use of the get/put_cpu_var() function in function refill_stock() from the memcontrol cgroup code lead to a "scheduling while atomic" warning. With this update, refill_stock() uses the get/put_cpu_light() function instead, and the warnings no longer appear. (BZ#1347171)

  • Prior to this update, if a real time task pinned to a given CPU was taking 100% of the CPU time, then calls to the lru_add_drain_all() function on other CPUs blocked for an undetermined amount of time. This caused latencies and undesired side effects. With this update, lru_add_drain_all() has been changed to drain the LRU pagevecs of remote CPUs. (BZ#1348523)

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

ProductVersionArch
Red Hat Enterprise Linux for Real Time7x86_64
Red Hat Enterprise Linux for Real Time for x86_64 - Extended Life Cycle Support7x86_64
Red Hat Enterprise Linux for Real Time for NFV7x86_64

Updated Packages

  • kernel-rt-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-debug-devel-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-3.10.0-327.28.2.rt56.234.el7_2.src.rpm
  • kernel-rt-trace-debuginfo-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-trace-kvm-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-debug-kvm-debuginfo-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-kvm-debuginfo-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-debug-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-debug-debuginfo-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-debuginfo-common-x86_64-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-devel-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-trace-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-trace-devel-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-trace-kvm-debuginfo-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-kvm-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-debuginfo-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-debug-kvm-3.10.0-327.28.2.rt56.234.el7_2.x86_64.rpm
  • kernel-rt-doc-3.10.0-327.28.2.rt56.234.el7_2.noarch.rpm

Fixes

CVEs

References

Additional information