(RHSA-2010:0439) 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 issue:

• a use-after-free flaw was found in the tcp_rcv_state_process() function
  in the Linux kernel TCP/IP protocol suite implementation. If a system using
  IPv6 had the IPV6_RECVPKTINFO option set on a listening socket, a remote
  attacker could send an IPv6 packet to that system, causing a kernel panic
  (denial of service). (CVE-2010-1188, Important)

This update also fixes the following bugs:

• a memory leak occurred when reading files on an NFS file system that was
  mounted with the “noac” option, causing memory to slowly be consumed.
  Unmounting the file system did not free the memory. With this update, the
  memory is correctly freed, which resolves this issue. (BZ#588221)

• the RHSA-2009:0225 update fixed a bug where, in some cases, on systems
  with the kdump service enabled, pressing Alt+SysRq+C to trigger a crash
  resulted in a system hang; therefore, the system did not restart and boot
  the dump-capture kernel as expected; no vmcore file was logged; and the
  following message was displayed on the console:

BUG: warning at arch/[arch]/kernel/crash.c:[xxx]/nmi_shootdown_cpus() (Not
tainted)

The RHSA-2009:0225 update resolved this issue by not calling printk()
during a crash. It was later discovered that this fix did not resolve the
issue in all cases, since there was one condition where printk() was
still being called: at a warning condition inside the mdelay() call.

This update replaces mdelay() calls with udelay(), where such a warning
condition does not exist, which fully resolves this issue, allowing
Alt+SysRq+C to work as expected. (BZ#588211)

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.