Important: kernel security and bug fix update

Updated kernel packages that fix multiple security issues and one bug are
now available for Red Hat Enterprise Linux 5.2 Extended Update Support.

This update has been rated as having important security impact by the Red
Hat Security Response Team.

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

This update fixes the following security issues:

* a system with SELinux enforced was more permissive in allowing local
users in the unconfined_t domain to map low memory areas even if the
mmap_min_addr restriction was enabled. This could aid in the local
exploitation of NULL pointer dereference bugs. (CVE-2009-2695, Important)

* 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)

This update also fixes the following bug:

* a bug in the IPv6 implementation in the Linux kernel could have caused an
unbalanced reference count. When using network bonding, this bug may have
caused a hang when shutting the system down via "shutdown -h", or prevented
the network service from being stopped via "service network stop".
(BZ#538409)

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.

Before applying this update, make sure that all previously-released
errata relevant to your system have been applied.

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259

517830 - CVE-2009-2695 kernel: SELinux and mmap_min_addr
530490 - CVE-2009-3547 kernel: fs: pipe.c null pointer dereference
538409 - Unbalance reference count in ndisc_recv_ns [rhel-5.2.z]

https://www.redhat.com/security/data/cve/CVE-2009-2695.html
https://www.redhat.com/security/data/cve/CVE-2009-3547.html
http://www.redhat.com/security/updates/classification/#important
http://kbase.redhat.com/faq/docs/DOC-20481
http://kbase.redhat.com/faq/docs/DOC-18042