The kernel packages contain the Linux kernel, the core of any Linux operating system. This update fixes the following security issues: * A buffer overflow flaw was found in the way the Linux kernel"s XFS file system implementation handled links with overly long path names. A local, unprivileged user could use this flaw to cause a denial of service or escalate their privileges by mounting a specially-crafted disk. * The fix for CVE-2011-2482 provided by RHSA-2011:1212 introduced a regression: on systems that do not have Security-Enhanced Linux in Enforcing mode, a socket lock race could occur between sctp_rcv and sctp_accept. A remote attacker could use this flaw to cause a denial of service. By default, SELinux runs in Enforcing mode on Red Hat Enterprise Linux 5. * The proc file system could allow a local, unprivileged user to obtain sensitive information or possibly cause integrity issues. * A missing validation flaw was found in the Linux kernel"s m_stop implementation. A local, unprivileged user could use this flaw to trigger a denial of service. * A flaw was found in the Linux kernel"s Journaling Block Device . A local attacker could use this flaw to crash the system by mounting a specially-crafted ext3 or ext4 disk. * A flaw was found in the Linux kernel"s encode_share_access implementation. A local, unprivileged user could use this flaw to trigger a denial of service by creating a regular file on an NFSv4 file system via mknod. * A flaw was found in the Linux kernel"s NFS implementation. A local, unprivileged user could use this flaw to cause a denial of service. * A missing boundary check was found in the Linux kernel"s HFS file system implementation. A local attacker could use this flaw to cause a denial of service or escalate their privileges by mounting a specially-crafted disk. Red Hat would like to thank Kees Cook for reporting CVE-2011-1020, and Clement Lecigne for reporting CVE-2011-4330. This update also fixes several bugs and adds one enhancement. Documentation for these changes will be available shortly from the Technical Notes document linked to in the References section. Users should upgrade to these updated packages, which contain backported patches to correct these issues, and fix the bugs and add the enhancement noted in the Technical Notes. The system must be rebooted for this update to take effect.