(RHSA-2013:1790) 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 Xen hypervisor handled
  error conditions when reading guest memory during certain guest-originated
  operations, such as port or memory mapped I/O writes. A privileged user in
  a fully-virtualized guest could use this flaw to leak hypervisor stack
  memory to a guest. (CVE-2013-4355, Moderate)

Red Hat would like to thank the Xen project 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#1014715)

• Due to a bug in the tg3 driver, systems that had the Wake-on-LAN (WOL)
  feature enabled on their NICs could not have been woken up from suspension
  or hibernation using WOL. A missing pci_wake_from_d3() function call has
  been added to the tg3 driver, which ensures that WOL functions properly by
  setting the PME_ENABLE bit. (BZ#1014973)

• Due to an incorrect test condition in the mpt2sas driver, the driver was
  unable to catch failures to map a SCSI scatter-gather list. The test
  condition has been corrected so that the mpt2sas driver now handles SCSI
  scatter-gather mapping failures as expected. (BZ#1018458)

• 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 packed 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#1023348)

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.