Red Hat Enterprise Linux 5.2 RHSA-2009:1672-01 Vital 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 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.