RHSA-2016:0617 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 6.6 Extended
Update Support.

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):

• It was found that the fix for CVE-2015-1805 incorrectly kept buffer offset and

buffer length in sync on a failed atomic read, potentially resulting in a pipe
buffer state corruption. A local, unprivileged user could use this flaw to crash
the system or leak kernel memory to user space. (CVE-2016-0774, Moderate)

The security impact of this issue was discovered by Red Hat.

Bug Fix(es):

• Due to prematurely decremented calc_load_task, the calculated load average was

off by up to the number of CPUs in the machine. As a consequence, job scheduling
worked improperly causing a drop in the system performance. This update keeps
the delta of the CPU going into NO_HZ idle separately, and folds the pending
idle delta into the global active count while correctly aging the averages for
the idle-duration when leaving NO_HZ mode. Now, job scheduling works correctly,
ensuring balanced CPU load. (BZ#1308968)

• Previously, the Stream Control Transmission Protocol (SCTP) retransmission

path selection was not fully RFC compliant when Partial Failover had been
enabled. The provided patch provides SCTP path selection updates, thus fixing
this bug. (BZ#1306565)

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 for x86_64 - Extended Update Support 6.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.6 i386
• Red Hat Enterprise Linux Server - AUS 6.6 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.6 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.6 ppc64
• Red Hat Enterprise Linux Server - TUS 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.6 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.6 i386
• Red Hat Enterprise Linux EUS Compute Node 6.6 x86_64

Fixes

• BZ - 1303961 - CVE-2016-0774 kernel: pipe buffer state corruption after unsuccessful atomic read from pipe

CVEs

• CVE-2016-0774

References

• https://access.redhat.com/security/updates/classification/#moderate