(RHSA-2013:1860) Moderate: kernel security and bug fix update

The kernel packages contain the Linux kernel, the core of any Linux
operating system.

• 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)

Red Hat would like to thank Fujitsu for reporting this issue.

This update also fixes the following bugs:

• A previous fix to the kernel did not contain a memory barrier in the
  percpu_up_write() function. Consequently, under certain circumstances, a race
  condition could occur, leading to memory corruption and a subsequent kernel
  panic. This update introduces a new memory barrier pair, light_mb() and
  heavy_mb(), for per-CPU basis read and write semaphores (percpu-rw-semaphores)
  ensuring that the race condition can no longer occur. In addition, the read path
  performance of “percpu-rw-semaphores” has been improved. (BZ#884735)

• Due to several related bugs in the be2net driver, the driver did not handle
  firmware manipulation of the network cards using the Emulex XE201 I/O controller
  properly. As a consequence, these NICs could not recover from an error
  successfully. A series of patches has been applied that fix the initialization
  sequence, and firmware download and activation for the XE201 controller. Error
  recovery now works as expected for the be2net NICs using the Emulex XE201 I/O
  controller. (BZ#1019892)

• A bug in the be2net driver could cause packet corruption when handling
  VLAN-tagged packets with no assigned VLAN group. This happened because the
  be2net driver called a function responsible for VLAN tag reinsertion in a wrong
  order in the code. The code has been restructured and the be2net driver now
  calls the __vlan_put_tag() function correctly, thus avoiding the packet
  corruption. (BZ#1019893)

• A previous patch to the kernel introduced the “VLAN tag re-insertion”
  workaround to resolve a problem with incorrectly handled VLAN-tagged packets
  with no assigned VLAN group while the be2net driver was in promiscuous mode.
  However, this solution led to packet corruption and a subsequent kernel oops if
  such a processed packet was a GRO packet. Therefore, a patch has been applied to
  restrict VLAN tag re-insertion only to non-GRO packets. The be2net driver now
  processes VLAN-tagged packets with no assigned VLAN group correctly in this
  situation. (BZ#1023347)

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.