(RHSA-2012:1129) Important: kernel security and bug fix update

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

This update fixes the following security issues:

• A NULL pointer dereference flaw was found in the nf_ct_frag6_reasm()
  function in the Linux kernel’s netfilter IPv6 connection tracking
  implementation. A remote attacker could use this flaw to send
  specially-crafted packets to a target system that is using IPv6 and also
  has the nf_conntrack_ipv6 kernel module loaded, causing it to crash.
  (CVE-2012-2744, Important)

• A flaw was found in the way the Linux kernel’s Event Poll (epoll)
  subsystem handled large, nested epoll structures. A local, unprivileged
  user could use this flaw to cause a denial of service. (CVE-2011-1083,
  Moderate)

Red Hat would like to thank an anonymous contributor working with the
Beyond Security SecuriTeam Secure Disclosure program for reporting
CVE-2012-2744, and Nelson Elhage for reporting CVE-2011-1083.

This update also fixes the following bugs:

• Attempting to turn on Data Center Bridging (DCB) on a port connected to a
  non-DCB switch port caused the system to become unresponsive or even
  terminate. This was because napi_poll routines in the ixgbe driver did not
  end the NAPI when data processing was complete. With this update, the ixgbe
  napi_poll routines have been fixed so that they now call the
  napi_complete() function when data processing has finished. This ensures
  that the NAPI is correctly disabled, and thus prevents possible hangs and
  crashes in this scenario. (BZ#814454)

• If a new file was created on a Network File System version 4 (NFSv4)
  share, the ownership was set to nfsnobody (-2) until it was possible to
  upcall to the idmapper. As a consequence, subsequent file system operations
  could incorrectly use “-2” for the user and group IDs for the given file,
  causing certain operations to fail. In reported cases, this issue also
  caused “Viminfo file is not writable” errors for users running Vim with
  files on an NFSv4 share. (BZ#820962)

• Previously, the size of the multicast IGMP (Internet Group Management
  Protocol) snooping hash table for a bridge was limited to 256 entries even
  though the maximum is 512. This was due to the hash table size being
  incorrectly compared to the maximum hash table size, hash_max, and the
  following message could have been produced by the kernel:

  Multicast hash table maximum reached, disabling snooping: vnet1, 512

With this update, the hash table value is correctly compared to the
hash_max value, and the error message no longer occurs under these
circumstances. (BZ#840021)

Users should upgrade to these updated packages, which contain backported
patches to resolve these issues. The system must be rebooted for this
update to take effect.