The kernel packages contain the Linux kernel, the core of any Linux operating system. This update fixes the following security issues: * Numerous reference count leaks were found in the Linux kernel"s block layer I/O context handling implementation. This could allow a local, unprivileged user to cause a denial of service. * A flaw was found in the Linux kernel"s cifs_lookup implementation. POSIX open during lookup should only be supported for regular files. When non-regular files are opened on lookup, it could cause a denial of service. * It was found that the Linux kernel"s register set common infrastructure implementation did not check if the required get and set handlers were initialized. A local, unprivileged user could use this flaw to cause a denial of service by performing a register set operation with a ptrace PTRACE_SETREGSET or PTRACE_GETREGSET request. Red Hat would like to thank H. Peter Anvin for reporting CVE-2012-1097. This update also fixes several bugs and adds various enhancements. 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 enhancements noted in the Technical Notes. The system must be rebooted for this update to take effect.