Important: kernel security and bug fix update

Synopsis

Important: kernel security and bug fix update

Type/Severity

Security Advisory: Important

Topic

Updated kernel packages that fix three security issues and several bugs are
now available for Red Hat Enterprise Linux 6.3 Extended Update Support.

The Red Hat Security Response Team 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 packages contain the Linux kernel, the core of any Linux
operating system.

• A race condition was found in the way asynchronous I/O and fallocate()
  interacted when using the ext4 file system. A local, unprivileged user
  could use this flaw to expose random data from an extent whose data blocks
  have not yet been written, and thus contain data from a deleted file.
  (CVE-2012-4508, Important)
  
• An information leak flaw was found in the way the Linux kernel's device
  mapper subsystem, under certain conditions, interpreted data written to
  snapshot block devices. An attacker could use this flaw to read data from
  disk blocks in free space, which are normally inaccessible. (CVE-2013-4299,
  Moderate)
  
• A format string flaw was found in the Linux kernel's block layer.
  A privileged, local user could potentially use this flaw to escalate their
  privileges to kernel level (ring0). (CVE-2013-2851, Low)
  

Red Hat would like to thank Theodore Ts'o for reporting CVE-2012-4508,
Fujitsu for reporting CVE-2013-4299, and Kees Cook for reporting
CVE-2013-2851. Upstream acknowledges Dmitry Monakhov as the original
reporter of CVE-2012-4508.

This update also fixes several bugs. Documentation for these changes will
be available shortly from the Technical Notes document linked to in the
References section.

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.

This update is available via the Red Hat Network. Details on how to use the
Red Hat Network to apply this update are available at
https://access.redhat.com/site/articles/11258

To install kernel packages manually, use "rpm -ivh [package]". Do not use
"rpm -Uvh" as that will remove the running kernel binaries from your
system. You may use "rpm -e" to remove old kernels after determining that
the new kernel functions properly on your system.

Affected Products

• Red Hat Enterprise Linux Server - Extended Update Support 6.3 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support 6.3 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.3 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.3 ppc64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 i386
• Red Hat Enterprise Linux EUS Compute Node 6.3 x86_64

Fixes

• BZ - 869904 - CVE-2012-4508 kernel: ext4: AIO vs fallocate stale data exposure
• BZ - 969515 - CVE-2013-2851 kernel: block: passing disk names as format strings
• BZ - 1004233 - CVE-2013-4299 kernel: dm: dm-snapshot data leak

CVEs

• CVE-2012-4508
• CVE-2013-2851
• CVE-2013-4299

References

• https://access.redhat.com/security/updates/classification/#important
• https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/6.3_Technical_Notes/kernel.html