(RHSA-2015:1787) Important: kernel-rt security, bug fix, and enhancement update

The kernel-rt packages contain the Linux kernel, the core of any Linux
operating system.

• Two flaws were found in the way the Linux kernel’s networking
  implementation handled UDP packets with incorrect checksum values. A remote
  attacker could potentially use these flaws to trigger an infinite loop in
  the kernel, resulting in a denial of service on the system, or cause a
  denial of service in applications using the edge triggered epoll
  functionality. (CVE-2015-5364, CVE-2015-5366, Important)

• A flaw was found in the way the Linux kernel’s ext4 file system handled
  the “page size > block size” condition when the fallocate zero range
  functionality was used. A local attacker could use this flaw to crash the
  system. (CVE-2015-0275, Moderate)

• It was found that the Linux kernel’s keyring implementation would leak
  memory when adding a key to a keyring via the add_key() function. A local
  attacker could use this flaw to exhaust all available memory on the system.
  (CVE-2015-1333, Moderate)

• A race condition flaw was found in the way the Linux kernel’s SCTP
  implementation handled Address Configuration lists when performing Address
  Configuration Change (ASCONF). A local attacker could use this flaw to
  crash the system via a race condition triggered by setting certain ASCONF
  options on a socket. (CVE-2015-3212, Moderate)

• An information leak flaw was found in the way the Linux kernel’s Virtual
  Dynamic Shared Object (vDSO) implementation performed address
  randomization. A local, unprivileged user could use this flaw to leak
  kernel memory addresses to user-space. (CVE-2014-9585, Low)

Red Hat would like to thank Canonical for reporting the CVE-2015-1333
issue. The CVE-2015-0275 issue was discovered by Xiong Zhou of Red Hat, and
the CVE-2015-3212 issue was discovered by Ji Jianwen of Red Hat
Engineering.

This update provides a build of the kernel-rt package for Red Hat
Enterprise MRG 2.5 that is layered on Red Hat Enterprise Linux 6, and fixes
the following issues:

• Fix regression in scsi_send_eh_cmnd()

• boot hangs at “Console: switching to colour dummy device 80x25”

• Update tcp stack to 3.17 kernel

• ksoftirqd high CPU usage due to stray tasklet from ioatdma driver

(BZ#1245345)

This update also fixes the following bugs:

• The configuration option CONFIG_RTC_HCTOSYS was disabled on the realtime
  kernel causing the RTC clock to be adjusted with the UTC time even if the
  system is configured to set the RTC to the local time. By enabling the
  CONFIG_RTC_HCTOSYS configuration option, when the system is configured to
  use local time, RTC will correctly update with the local time and not try
  to use another timezone. (BZ#1248047)

• In the realtime kernel, if a rt_mutex was taken while in interrupt
  context the normal priority inheritance protocol would falsely identify a
  deadlock and trigger a kernel crash. The patch that added the rt_mutex in
  this interrupt context was reverted. (BZ#1250649)

All kernel-rt users are advised to upgrade to these updated packages, which
correct these issues and add these enhancements. The system must be
rebooted for this update to take effect.