RHSA-2015:0751: Important: kernel-rt security and bug fix update

The kernel-rt packages contain the Linux kernel, the core of any Linuxoperating system. It was found that the Linux kernel's Infiniband subsystem did not properly sanitize input parameters while registering memory regions fromuser space via the (u)verbs API. A local user with access to a/dev/infiniband/uverbsX device could use this flaw to crash the system or,potentially, escalate their privileges on the system. (CVE-2014-8159,Important) A use-after-free flaw was found in the way the Linux kernel's SCTP implementation handled authentication key reference counting during INITcollisions. A remote attacker could use this flaw to crash the system or,potentially, escalate their privileges on the system. (CVE-2015-1421,Important)Red Hat would like to thank Mellanox for reporting the CVE-2014-8159 issue.The CVE-2015-1421 issue was discovered by Sun Baoliang of Red Hat.The MRG-Realtime 3.10 kernel-rt sources have been updated to include thefollowing bug fixes: The kdump service could become unresponsive due to a deadlock in the kernel call ioapiclock. Attempt to make metadata changes such as creating a thin device or snapshot thin device did not error out cleanly.(BZ#1201384)This update also fixes the following bug: The MRG kernel scheduler code was missing checks for the PREEMPTLAZY flag allowing tasks to be preempted more times than necessary causinglatency spikes on the system. Additional checks for the PREEMPTLAZY flagwere added to the checkpreemptwakeup() and checkpreemptcurr() functionsin the scheduler code so that preempt wakeups were reduced and theselatency spikes were removed. (BZ#1157949)All kernel-rt users are advised to upgrade to these updated packages, whichcorrect these issues. The system must be rebooted for this update to takeeffect.