Issued:
2017-04-12
Updated:
2017-04-12

RHSA-2017:0931 - 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.

Security Fix(es):

  • A race condition flaw was found in the N_HLDC Linux kernel driver when accessing n_hdlc.tbuf list that can lead to double free. A local, unprivileged user able to set the HDLC line discipline on the tty device could use this flaw to increase their privileges on the system. (CVE-2017-2636, Important)

  • A flaw was found in the Linux kernel key management subsystem in which a local attacker could crash the kernel or corrupt the stack and additional memory (denial of service) by supplying a specially crafted RSA key. This flaw panics the machine during the verification of the RSA key. (CVE-2016-8650, Moderate)

  • A flaw was found in the Linux kernel's implementation of setsockopt for the SO_{SND|RCV}BUFFORCE setsockopt() system call. Users with non-namespace CAP_NET_ADMIN are able to trigger this call and create a situation in which the sockets sendbuff data size could be negative. This could adversely affect memory allocations and create situations where the system could crash or cause memory corruption. (CVE-2016-9793, Moderate)

  • A flaw was found in the Linux kernel's handling of clearing SELinux attributes on /proc/pid/attr files. An empty (null) write to this file can crash the system by causing the system to attempt to access unmapped kernel memory. (CVE-2017-2618, Moderate)

Red Hat would like to thank Alexander Popov for reporting CVE-2017-2636 and Ralf Spenneberg for reporting CVE-2016-8650. The CVE-2017-2618 issue was discovered by Paul Moore (Red Hat Engineering).

Bug Fix(es):

  • Previously, a cgroups data structure was sometimes corrupted due to a race condition in the kernel-rt cgroups code. Consequently, several system tasks were blocked, and the operating system became unresponsive. This update adds a lock that prevents the race condition. As a result, the cgroups data structure no longer gets corrupted and the operating system no longer hangs under the described circumstances. (BZ#1420784)

  • The kernel-rt packages have been upgraded to the 3.10.0-514.16.1 source tree, which provides a number of bug fixes over the previous version. (BZ#1430749)

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-trace-kvm-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-doc-3.10.0-514.16.1.rt56.437.el7.noarch.rpm
  • kernel-rt-debug-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-debug-kvm-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-debuginfo-common-x86_64-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-kvm-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-trace-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-debug-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-trace-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-kvm-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-debug-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-3.10.0-514.16.1.rt56.437.el7.src.rpm
  • kernel-rt-trace-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-debug-kvm-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm
  • kernel-rt-trace-kvm-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm

Fixes

CVEs

References

Additional information