(RHSA-2012:0350) 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 buffer overflow flaw was found in the way the Linux kernel’s XFS file
  system implementation handled links with overly long path names. A local,
  unprivileged user could use this flaw to cause a denial of service or
  escalate their privileges by mounting a specially-crafted disk.
  (CVE-2011-4077, Moderate)

• Flaws in ghash_update() and ghash_final() could allow a local,
  unprivileged user to cause a denial of service. (CVE-2011-4081, Moderate)

• A flaw was found in the Linux kernel’s Journaling Block Device (JBD). A
  local, unprivileged user could use this flaw to crash the system by
  mounting a specially-crafted ext3 or ext4 disk. (CVE-2011-4132, Moderate)

• It was found that the kvm_vm_ioctl_assign_device() function in the KVM
  (Kernel-based Virtual Machine) subsystem of a Linux kernel did not check if
  the user requesting device assignment was privileged or not. A local,
  unprivileged user on the host could assign unused PCI devices, or even
  devices that were in use and whose resources were not properly claimed by
  the respective drivers, which could result in the host crashing.
  (CVE-2011-4347, Moderate)

• Two flaws were found in the way the Linux kernel’s __sys_sendmsg()
  function, when invoked via the sendmmsg() system call, accessed user-space
  memory. A local, unprivileged user could use these flaws to cause a denial
  of service. (CVE-2011-4594, Moderate)

• The RHSA-2011:1530 kernel update introduced an integer overflow flaw in
  the Linux kernel. On PowerPC systems, a local, unprivileged user could use
  this flaw to cause a denial of service. (CVE-2011-4611, Moderate)

• A flaw was found in the way the KVM subsystem of a Linux kernel handled
  PIT (Programmable Interval Timer) IRQs (interrupt requests) when there was
  no virtual interrupt controller set up. A local, unprivileged user on the
  host could force this situation to occur, resulting in the host crashing.
  (CVE-2011-4622, Moderate)

• A flaw was found in the way the Linux kernel’s XFS file system
  implementation handled on-disk Access Control Lists (ACLs). A local,
  unprivileged user could use this flaw to cause a denial of service or
  escalate their privileges by mounting a specially-crafted disk.
  (CVE-2012-0038, Moderate)

• A flaw was found in the way the Linux kernel’s KVM hypervisor
  implementation emulated the syscall instruction for 32-bit guests. An
  unprivileged guest user could trigger this flaw to crash the guest.
  (CVE-2012-0045, Moderate)

• A divide-by-zero flaw was found in the Linux kernel’s igmp_heard_query()
  function. An attacker able to send certain IGMP (Internet Group Management
  Protocol) packets to a target system could use this flaw to cause a denial
  of service. (CVE-2012-0207, Moderate)

Red Hat would like to thank Nick Bowler for reporting CVE-2011-4081; Sasha
Levin for reporting CVE-2011-4347; Tetsuo Handa for reporting
CVE-2011-4594; Maynard Johnson for reporting CVE-2011-4611; Wang Xi for
reporting CVE-2012-0038; Stephan Bärwolf for reporting CVE-2012-0045; and
Simon McVittie for reporting CVE-2012-0207. Upstream acknowledges Mathieu
Desnoyers as the original reporter of CVE-2011-4594.

This update also fixes several bugs. Documentation for these changes will
be available shortly from the Technical Notes document linked to in the
References section.

Users should upgrade to these updated packages, which contain backported
patches to correct these issues, and fix the bugs noted in the Technical
Notes. The system must be rebooted for this update to take effect.