RHSA-2014:0900: Important: kernel security and bug fix update

The kernel packages contain the Linux kernel, the core of any Linuxoperating system. A flaw was found in the way the Linux kernel's futex subsystem handled the requeuing of certain Priority Inheritance (PI) futexes. A local,unprivileged user could use this flaw to escalate their privileges on thesystem. (CVE-2014-3153, Important) A flaw was found in the way the Linux kernel's floppy driver handled user space provided data in certain error code paths while processing FDRAWCMDIOCTL commands. A local user with write access to /dev/fdX could use thisflaw to free (using the kfree() function) arbitrary kernel memory.(CVE-2014-1737, Important) It was found that the Linux kernel's floppy driver leaked internal kernel memory addresses to user space during the processing of the FDRAWCMD IOCTLcommand. A local user with write access to /dev/fdX could use this flaw toobtain information about the kernel heap arrangement. (CVE-2014-1738, Low)Note: A local user with write access to /dev/fdX could use these two flaws(CVE-2014-1737 in combination with CVE-2014-1738) to escalate theirprivileges on the system.Red Hat would like to thank Kees Cook of Google for reportingCVE-2014-3153, and Matthew Daley for reporting CVE-2014-1737 andCVE-2014-1738. Google acknowledges Pinkie Pie as the original reporter ofCVE-2014-3153.This update also fixes the following bug: A previous change that introduced global clock updates caused guest machines to boot slowly when the host Time Stamp Counter (TSC) was markedas unstable. The slow down increased with the number of vCPUs allocated.To resolve this problem, a patch has been applied to limit the rate of theglobal clock updates. (BZ#1102253)All kernel users are advised to upgrade to these updated packages, whichcontain backported patches to correct these issues. The system must berebooted for this update to take effect.