RHSA-2015:1211 - Security Advisory

Topic

Updated kernel packages that fix one security issue and two bugs are now
available for Red Hat Enterprise Linux 6.4 Advanced Update Support.

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

Description

The kernel 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)

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

This update also fixes the following bugs:

• The backlog data could previously not be consumed when the

audit_log_start() function was running even if audit_log_start() called the
wait_for_auditd() function to consume it. As only auditd could consume the
backlog data, audit_log_start() terminated unexpectedly. Consequently, the
system became unresponsive until the backlog timeout was up. With this
update, audit_log_start() no longer terminates and the system shuts down
and reboots gracefully in a timely manner. (BZ#1140489)

• Direct I/O writes extending a parallel file could previously race to

update the size of the file. If the writes executed in the out-of-order
manner, the file size could move backwards and push a previously completed
write beyond EOF, causing it to be lost. With this update, file size
updates are always executed in appropriate order, thus fixing this bug.
(BZ#1218497)

All kernel users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. 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 Server - AUS 6.4 x86_64

Fixes

• BZ - 1202855 - CVE-2015-1805 kernel: pipe: iovec overrun leading to memory corruption

CVEs

• CVE-2015-1805

References

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