Red Hat Enterprise Linux 5: RHSA-2016-0450-01 Critical Memory Issue

The kernel packages contain the Linux kernel, the core of any Linux operating system.
* An integer overflow flaw was found in the way the Linux kernel's Frame Buffer device implementation mapped kernel memory to user space via the mmap syscall. A local user able to access a frame buffer device file (/dev/fb*) could possibly use this flaw to escalate their privileges on the system. (CVE-2013-2596, Important)
* It was found that the Xen hypervisor x86 CPU emulator implementation did not correctly handle certain instructions with segment overrides, potentially resulting in a memory corruption. A malicious guest user could use this flaw to read arbitrary data relating to other guests, cause a denial of service on the host, or potentially escalate their privileges on the host. (CVE-2015-2151, Important)
This update also fixes the following bugs:
* Previously, the CPU power of a CPU group could be zero. As a consequence, a kernel panic occurred at "find_busiest_group+570" with do_divide_error. The provided patch ensures that the division is only performed if the CPU power is not zero, and the aforementioned panic no longer occurs. (BZ#1209728)
* Prior to this update, a bug occurred when performing an online resize of an ext4 file system which had been previously converted from ext3. As a consequence, the kernel crashed. The provided patch fixes online resizing for such file systems by limiting the blockgroup search loop for non-extent files, and the mentioned kernel crash no longer occurs. (BZ#1301100)
All kernel users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.