[RHSA-2011:0928] 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:

• It was found that the receive hook in the ipip_init() function in the
  ipip module, and in the ipgre_init() function in the ip_gre module, could
  be called before network namespaces setup is complete. If packets were
  received at the time the ipip or ip_gre module was still being loaded into
  the kernel, it could cause a denial of service. (CVE-2011-1767,
  CVE-2011-1768, Moderate)

• It was found that an mmap() call with the MAP_PRIVATE flag on "/dev/zero"
  would create transparent hugepages and trigger a certain robustness check.
  A local, unprivileged user could use this flaw to cause a denial of
  service. (CVE-2011-2479, Moderate)

This update also fixes various bugs. Documentation for these bug fixes 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 resolve these issues, and fix the bugs noted in the Technical
Notes. The system must be rebooted for this update to take effect.