(RHSA-2009:1541) Important: kernel security update

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

This update fixes the following security issues:

• a NULL pointer dereference flaw was found in each of the following
  functions in the Linux kernel: pipe_read_open(), pipe_write_open(), and
  pipe_rdwr_open(). When the mutex lock is not held, the i_pipe pointer could
  be released by other processes before it is used to update the pipe’s
  reader and writer counters. This could lead to a local denial of service or
  privilege escalation. (CVE-2009-3547, Important)

Users should upgrade to these updated packages, which contain a backported
patch to correct these issues. The system must be rebooted for this update
to take effect.