[RHSA-2016:1532-02] Important: kernel-rt security and bug fix update

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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

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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 . More contact

details at https://access.redhat.com/security/team/contact/

 

Copyright 2016 Red Hat, Inc.

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