(RHSA-2013:1783) Important: kernel security and bug fix update

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.