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=====================================================================
                   Red Hat Security Advisory

Synopsis:          Important: kernel-rt security and bug fix update
Advisory ID:       RHSA-2016:1532-02
Product:           Red Hat Enterprise MRG for RHEL-6
Advisory URL:      https://rhn.redhat.com/errata/RHSA-2016-1532.html
Issue date:        2016-08-02
CVE Names:         CVE-2015-8660 CVE-2016-4470 
=====================================================================

1. Summary:

An update for kernel-rt is now available for Red Hat Enterprise MRG 2.5.

Red Hat Product Security has rated this update as having a security impact
of Important. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available for each vulnerability
from the CVE link(s) in the References section.

2. Relevant releases/architectures:

MRG Realtime for RHEL 6 Server v.2 - noarch, x86_64

3. Description:

The kernel-rt packages provide the Real Time Linux Kernel, which enables
fine-tuning for systems with extremely high determinism requirements.

* A flaw was found in the Linux kernel's keyring handling code, where in
key_reject_and_link() an uninitialised variable would eventually lead to
arbitrary free address which could allow attacker to use a use-after-free
style attack. (CVE-2016-4470, Important)

* The ovl_setattr function in fs/overlayfs/inode.c in the Linux kernel
through 4.3.3 attempts to merge distinct setattr operations, which allows
local users to bypass intended access restrictions and modify the
attributes of arbitrary overlay files via a crafted application.
(CVE-2015-8660, Moderate)

Red Hat would like to thank Nathan Williams for reporting CVE-2015-8660.
The CVE-2016-4470 issue was discovered by David Howells (Red Hat Inc.).

The kernel-rt packages have been upgraded to upstream version
3.10.0-327.rt56.194.el6rt, which provides a number of bug fixes over the
previous version. (BZ#1343658)

This update also fixes the following bugs:

* Previously, use of the get/put_cpu_var() function in function
refill_stock() from the memcontrol cgroup code lead to a "scheduling while
atomic" warning. With this update, refill_stock() uses the
get/put_cpu_light() function instead, and the warnings no longer appear.
(BZ#1348710)

* Prior to this update, if a real time task pinned to a given CPU was
taking 100% of the CPU time, then calls to the lru_add_drain_all() function
on other CPUs blocked for an undetermined amount of time. This caused
latencies and undesired side effects. With this update, lru_add_drain_all()
has been changed to drain the LRU pagevecs of remote CPUs. (BZ#1348711)

4. Solution:

For details on how to apply this update, which includes the changes
described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.

5. Bugs fixed (https://bugzilla.redhat.com/):

1291329 - CVE-2015-8660 kernel: Permission bypass on overlayfs during copy_up
1341716 - CVE-2016-4470 kernel: Uninitialized variable in request_key handling causes kernel crash in error handling path
1343658 - update the MRG 2.5.z 3.10 kernel-rt sources

6. Package List:

MRG Realtime for RHEL 6 Server v.2:

Source:
kernel-rt-3.10.0-327.rt56.194.el6rt.src.rpm

noarch:
kernel-rt-doc-3.10.0-327.rt56.194.el6rt.noarch.rpm
kernel-rt-firmware-3.10.0-327.rt56.194.el6rt.noarch.rpm

x86_64:
kernel-rt-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-debug-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-debug-debuginfo-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-debug-devel-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-debuginfo-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-debuginfo-common-x86_64-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-devel-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-trace-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-trace-debuginfo-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-trace-devel-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-vanilla-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-vanilla-debuginfo-3.10.0-327.rt56.194.el6rt.x86_64.rpm
kernel-rt-vanilla-devel-3.10.0-327.rt56.194.el6rt.x86_64.rpm

These packages are GPG signed by Red Hat for security.  Our key and
details on how to verify the signature are available from
https://access.redhat.com/security/team/key/

7. References:

https://access.redhat.com/security/cve/CVE-2015-8660
https://access.redhat.com/security/cve/CVE-2016-4470
https://access.redhat.com/security/updates/classification/#important

8. Contact:

The Red Hat security contact is <secalert@redhat.com>. More contact
details at https://access.redhat.com/security/team/contact/

Copyright 2016 Red Hat, Inc.
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