(RHSA-2011:1419) Moderate: 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:

• The way IPv4 and IPv6 protocol sequence numbers and fragment IDs were
  generated could allow a man-in-the-middle attacker to inject packets and
  possibly hijack connections. Protocol sequence numbers and fragment IDs are
  now more random. (CVE-2011-3188, Moderate)

• A flaw was found in the Linux kernel’s clock implementation on 32-bit,
  SMP (symmetric multiprocessing) systems. A local, unprivileged user could
  use this flaw to cause a divide error fault, resulting in a denial of
  service. (CVE-2011-3209, Moderate)

Red Hat would like to thank Dan Kaminsky for reporting CVE-2011-3188, and
Yasuaki Ishimatsu for reporting CVE-2011-3209.

In addition, this update fixes the following bugs:

• When the Global File System 2 (GFS2) file system is suspended, its delete
  work queue is also suspended, along with any pending work on the queue.
  Prior to this update, if GFS2’s transaction lock was demoted while the
  delete work queue was suspended, a deadlock could occur on the file system
  because the file system tried to flush the work queue in the lock demotion
  code. With this update, the delete work queue is no longer flushed by the
  lock demotion code, and a deadlock no longer occurs. Instead, the work
  queue is flushed by the unmount operation, so that pending work is properly
  completed. (BZ#733678)

• A previously applied patch introduced a regression for third-party file
  systems that do not set the FS_HAS_IODONE2 flag, specifically, Oracle
  Cluster File System 2 (OCFS2). The patch removed a call to the aio_complete
  function, resulting in no completion events being processed, causing
  user-space applications to become unresponsive. This update reintroduces
  the aio_complete function call, fixing this issue. (BZ#734156)

• Certain devices support multiple operation modes. For example, EMC
  CLARiiON disk arrays support ALUA mode and their own vendor specific mode
  for failover. In Red Hat Enterprise Linux 5.5, a bug was discovered that
  prevented tools such as multipath from being able to select the
  device/hardware handler plug-in to use. This resulted in the application
  (for example, multipath) not working properly. With this update, the kernel
  has been modified to allow applications to select the device/hardware
  handler to use, thus resolving this issue. (BZ#739900)

• This update improves the performance of delete/unlink operations in a
  GFS2 file system with large files by adding a layer of metadata read-ahead
  for indirect blocks. (BZ#743805)

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