(RHSA-2013:0882) 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 flaw was found in the way the vhost kernel module handled descriptors
  that spanned multiple regions. A privileged guest user in a KVM
  (Kernel-based Virtual Machine) guest could use this flaw to crash the host
  or, potentially, escalate their privileges on the host. (CVE-2013-0311,
  Important)

• A flaw was found in the way the KVM subsystem handled guests attempting
  to run with the X86_CR4_OSXSAVE CPU feature flag set. On hosts without the
  XSAVE CPU feature, a local, unprivileged user could use this flaw to crash
  the host system. (The “grep --color xsave /proc/cpuinfo” command can be
  used to verify if your system has the XSAVE CPU feature.) (CVE-2012-4461,
  Moderate)

• It was found that the default SCSI command filter does not accommodate
  commands that overlap across device classes. A privileged guest user could
  potentially use this flaw to write arbitrary data to a LUN that is
  passed-through as read-only. (CVE-2012-4542, Moderate)

• A use-after-free flaw was found in the tmpfs implementation. A local user
  able to mount and unmount a tmpfs file system could use this flaw to cause
  a denial of service or, potentially, escalate their privileges.
  (CVE-2013-1767, Low)

Red Hat would like to thank Jon Howell for reporting CVE-2012-4461.
CVE-2012-4542 was discovered by Paolo Bonzini of Red Hat.

This update also fixes the following bugs:

• Previously, when open(2) system calls were processed, the GETATTR
  routine did not check to see if valid attributes were also returned. As a
  result, the open() call succeeded with invalid attributes instead of
  failing in such a case. This update adds the missing check, and the open()
  call succeeds only when valid attributes are returned. (BZ#960409)

• Previously, the fsync(2) system call incorrectly returned the EIO
  (Input/Output) error instead of the ENOSPC (No space left on device) error.
  This was due to incorrect error handling in the page cache. This problem
  has been fixed and the correct error value is now returned. (BZ#960418)

• In the RPC code, when a network socket backed up due to high network
  traffic, a timer was set causing a retransmission, which in turn could
  cause an even larger amount of network traffic to be generated. To prevent
  this problem, the RPC code now waits for the socket to empty instead of
  setting the timer. (BZ#960423)

• This update fixes a number of bugs in the be2iscsi driver for
  ServerEngines BladeEngine 2 Open iSCSI devices. (BZ#955502)

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.