The kernel packages contain the Linux kernel, the core of any Linux operating system. This update fixes the following security issues: * An integer underflow flaw, leading to a buffer overflow, was found in the Linux kernel"s Datagram Congestion Control Protocol implementation. This could allow a remote attacker to cause a denial of service. * Missing sanity checks were found in setup_arg_pages in the Linux kernel. When making the size of the argument and environment area on the stack very large, it could trigger a BUG_ON, resulting in a local denial of service. * A missing validation check was found in the bcm_release and raw_release functions in the Linux kernel"s Controller Area Network implementation. This could allow a local, unprivileged user to cause a denial of service. * The fix for Red Hat Bugzilla bug 656461, as provided in RHSA-2011:0542, introduced a regression in the cifs_close function in the Linux kernel"s Common Internet File System implementation. A local, unprivileged user with write access to a CIFS file system could use this flaw to cause a denial of service. Red Hat would like to thank Dan Rosenberg for reporting CVE-2011-1770; Brad Spengler for reporting CVE-2010-3858; and Oliver Hartkopp for reporting CVE-2011-1748. This update also fixes various bugs. Documentation for these bug fixes 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 resolve these issues, and fix the bugs noted in the Technical Notes. The system must be rebooted for this update to take effect.