Updated kernel packages that fix multiple security issues and various bugs are now available for Red Hat Enterprise Linux 5.3 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 bugs: * a caching bug in nfs_readdir() has been resolved. This may have caused parts of directory listings to become stale, as they came from cached data when they should not have, possibly causing NFS clients to see duplicate files or not see all files in a directory. (BZ#526959) * a bug prevented the pciehp driver from detecting PCI Express hot plug slots on some systems. (BZ#530381) * when a process attempted to read from a page that had first been accessed by writing to part of it (via write(2)), the NFS client needed to flush the modified portion of the page out to the server, and then read the entire page back in. This flush caused performance issues. (BZ#521243) * a deadlock was found in the cciss driver. In rare cases, this caused an NMI lockup during boot. Messages such as "cciss: controller cciss[x] failed, stopping." and "cciss[x]: controller not responding." may have been displayed on the console. (BZ#525728) 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.