(RHSA-2013:0747) Moderate: 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 flaw was found in the Xen netback driver implementation in the Linux
  kernel. A privileged guest user with access to a para-virtualized network
  device could use this flaw to cause a long loop in netback, leading to a
  denial of service that could potentially affect the entire system.
  (CVE-2013-0216, Moderate)

• A flaw was found in the Xen PCI device back-end driver implementation in
  the Linux kernel. A privileged guest user in a guest that has a PCI
  passthrough device could use this flaw to cause a denial of service that
  could potentially affect the entire system. (CVE-2013-0231, Moderate)

• A NULL pointer dereference flaw was found in the IP packet transformation
  framework (XFRM) implementation in the Linux kernel. A local user who has
  the CAP_NET_ADMIN capability could use this flaw to cause a denial of
  service. (CVE-2013-1826, Moderate)

• Information leak flaws were found in the XFRM implementation in the
  Linux kernel. A local user who has the CAP_NET_ADMIN capability could use
  these flaws to leak kernel stack memory to user-space. (CVE-2012-6537, Low)

• An information leak flaw was found in the logical link control (LLC)
  implementation in the Linux kernel. A local, unprivileged user could use
  this flaw to leak kernel stack memory to user-space. (CVE-2012-6542, Low)

• Two information leak flaws were found in the Linux kernel’s Asynchronous
  Transfer Mode (ATM) subsystem. A local, unprivileged user could use these
  flaws to leak kernel stack memory to user-space. (CVE-2012-6546, Low)

• An information leak flaw was found in the TUN/TAP device driver in the
  Linux kernel’s networking implementation. A local user with access to a
  TUN/TAP virtual interface could use this flaw to leak kernel stack memory
  to user-space. (CVE-2012-6547, Low)

Red Hat would like to thank the Xen project for reporting the CVE-2013-0216
and CVE-2013-0231 issues.

This update also fixes the following bugs:

• The IPv4 code did not correctly update the Maximum Transfer Unit (MTU) of
  the designed interface when receiving ICMP Fragmentation Needed packets.
  Consequently, a remote host did not respond correctly to ping attempts.
  With this update, the IPv4 code has been modified so the MTU of the
  designed interface is adjusted as expected in this situation. The ping
  command now provides the expected output. (BZ#923353)

• Previously, the be2net code expected the last word of an MCC completion
  message from the firmware to be transferred by direct memory access (DMA)
  at once. However, this is not always true, and could therefore cause the
  BUG_ON() macro to be triggered in the be_mcc_compl_is_new() function,
  consequently leading to a kernel panic. The BUG_ON() macro has been
  removed from be_mcc_compl_is_new(), and the kernel panic no longer occurs
  in this scenario. (BZ#923910)

• Previously, the NFSv3 server incorrectly converted 64-bit cookies to
  32-bit. Consequently, the cookies became invalid, which affected all file
  system operations depending on these cookies, such as the READDIR operation
  that is used to read entries from a directory. This led to various
  problems, such as exported directories being empty or displayed
  incorrectly, or an endless loop of the READDIRPLUS procedure which could
  potentially cause a buffer overflow. This update modifies knfsd code so
  that 64-bit cookies are now handled correctly and all file system
  operations work as expected. (BZ#924087)

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