(RHSA-2015:1583) Moderate: kernel security and bug fix update

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

• It was found that the Linux kernel’s ping socket implementation did not
  properly handle socket unhashing during spurious disconnects, which could
  lead to a use-after-free flaw. On x86-64 architecture systems, a local user
  able to create ping sockets could use this flaw to crash the system.
  On non-x86-64 architecture systems, a local user able to create ping
  sockets could use this flaw to escalate their privileges on the system.
  (CVE-2015-3636, Moderate)

This update also fixes the following bugs:

• Previously, the bridge device did not propagate VLAN information to its
  ports and Generic Receive Offload (GRO) information to devices that sit on
  top. This resulted in lower receive performance of VLANs over bridge
  devices because GRO was not enabled. An attempt to resolve this problem was
  made with BZ#858198 by introducing a patch that allows VLANs to be
  registered with the participating bridge ports and adds GRO to the bridge
  device feature set, however, that attempt introduced a number of
  regressions, which broke the vast majority of stacked setups involving
  bridge devices and VLANs. This update reverts the patch provided by
  BZ#858198 and removes support for this capability. (BZ#1131697)

• The backlog data could previously not be consumed when the
  audit_log_start() function was running even if audit_log_start() called the
  wait_for_auditd() function to consume it. As only auditd could consume the
  backlog data, audit_log_start() terminated unexpectedly. Consequently, the
  system became unresponsive until the backlog timeout was up again.
  With this update, audit_log_start() no longer terminates and the system
  shuts down and reboots gracefully in a timely manner. (BZ#1140490)

• This update introduces a set of patches with a new VLAN model to conform
  to upstream standards. In addition, this set of patches fixes other issues
  such as transmission of Internet Control Message Protocol (ICMP) fragments.
  (BZ#1173560)

• Due to a bug in the audit code, a kernel panic occurred in the
  tasklist_lock variable if SELinux was in permissive or enforcing mode.
  A patch has been applied to fix this bug, and the operating system now
  continues to work normally. (BZ#1236103)

• If a server returned an empty or malformed READDIR response, the NFS
  client could previously terminate unexpectedly while attempting to decode
  that response. This update uses the response size to determine if existing
  pages of data are available for decoding, and the client only decodes the
  responses if they exist. As a result, the NFS client no longer attempts to
  decode pages of data that may not exist, and the aforementioned crash is
  thus avoided. (BZ#1232133)

• Previously, if a slave device had a receive handler registered, then an
  error unwind of bonding device enslave function became broken, which led to
  a kernel oops. This update detaches the slave in the unwind path, and the
  aforementioned oops no longer occurs. (BZ#1222482)

• Due to bad memory or memory corruption, an isolated BUG_ON(mm->nr_ptes)
  was sometimes reported, indicating that not all the page tables allocated
  could be found and freed when the exit_mmap() function cleared the user
  address space. As a consequence, a kernel panic occurred. To fix this bug,
  the BUG_ON() function has been replaced by WARN_ON(), which prevents the
  kernel from panicking in the aforementioned situation. (BZ#1235930)

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.