RHSA-2015:2587: Important: kernel security, bug fix, and enhancement 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 file system implementation handled rename operations in which the source was inside and thedestination was outside of a bind mount. A privileged user inside acontainer could use this flaw to escape the bind mount and, potentially,escalate their privileges on the system. (CVE-2015-2925, Important) It was found that the x86 ISA (Instruction Set Architecture) is prone to a denial of service attack inside a virtualized environment in the form ofan infinite loop in the microcode due to the way (sequential) delivering ofbenign exceptions such as #AC (alignment check exception) is handled.A privileged user inside a guest could use this flaw to create denial ofservice conditions on the host kernel. (CVE-2015-5307, Important) A race condition flaw was found in the way the Linux kernel's IPC subsystem initialized certain fields in an IPC object structure that werelater used for permission checking before inserting the object into aglobally visible list. A local, unprivileged user could potentially usethis flaw to elevate their privileges on the system. (CVE-2015-7613,Important)Red Hat would like to thank Ben Serebrin of Google Inc. for reporting theCVE-2015-5307 issue.This update also fixes the following bugs and adds one enhancement: When setting up an ESP IPsec connection, the aesctr algorithm did not work for ESP on a Power little endian VM host. As a consequence, a kernelerror was previously returned and the connection failed to be established.A set of patches has been provided to fix this bug, and aesctr works forESP in the described situation as expected. (BZ#1247127) The redistribute3() function distributed entries across 3 nodes. However, some entries were moved an incorrect way, breaking the ordering. As aresult, BUG() in the dm-btree-remove.c:shift() function occurred whenentries were removed from the btree. A patch has been provided to fix thisbug, and redistribute3() now works as expected. (BZ#1263945) When booting an mpt2sas adapter in a huge DDW enabled slot on Power, the kernel previously generated a warning followed by a call trace.The provided patch set enhances the Power kernel to be able to supportIOMMU as a fallback for the cases where the coherent mask of the device isnot suitable for direct DMA. As a result, neither the warning nor the calltrace occur in this scenario. (BZ#1267133) If the client mounted /exports and tried to execute the "chown -R" command across the entire mountpoint, a warning about a circular directorystructure was previously returned because mount points all had the sameinode number. A set of patches has been provided to fix this bug, and mountpoints are now assigned with unique inode numbers as expected. (BZ#1273239) Due to a validation error of in-kernel MMIO tracing, a VM became previously unresponsive when connected to Red Hat Enterprise VirtualizationHypervisor. The provided patch fixes this bug by dropping the check in MMIOhandler, and a VM continues running as expected. (BZ#1275149) The NFS client could previously fail to send a CLOSE operation if the file was opened with OWRONLY and the server restarted after the OPEN.Consequently, the server appeared in a state that could block other NFSoperations from completing. The client's state flags have been modified tocatch this condition and correctly CLOSE the file. (BZ#1275298) This update sets multicast filters for multicast packets when the interface is not in promiscuous mode. This change has an impact on the RARusage such that SR-IOV has some RARs reserved for its own usage as well.(BZ#1265091)All kernel users are advised to upgrade to these updated packages, whichcontain backported patches to correct these issues and add thisenhancement. The system must be rebooted for this update to take effect.