(RHSA-2012:0480) Important: kernel security, bug fix, and enhancement update

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

This update fixes the following security issue:

• A flaw in the xfrm6_tunnel_rcv() function in the Linux kernel’s IPv6
  implementation could lead to a use-after-free or double free flaw in
  tunnel6_rcv(). A remote attacker could use this flaw to send
  specially-crafted packets to a target system that is using IPv6 and also
  has the xfrm6_tunnel kernel module loaded, causing it to crash.
  (CVE-2012-1583, Important)

If you do not run applications that use xfrm6_tunnel, you can prevent the
xfrm6_tunnel module from being loaded by creating (as the root user) a
“/etc/modprobe.d/xfrm6_tunnel.conf” file, and adding the following line to
it:

blacklist xfrm6_tunnel

This way, the xfrm6_tunnel module cannot be loaded accidentally. A reboot
is not necessary for this change to take effect.

This update also fixes various bugs and adds an enhancement. 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 this issue, and fix the bugs and add the enhancement
noted in the Technical Notes. The system must be rebooted for this update
to take effect.