RHEL 7 : kernel-rt (RHSA-2017:0931)

This script is Copyright (C) 2017 Tenable Network Security, Inc.


Synopsis :

The remote Red Hat host is missing one or more security updates.

Description :

An update for kernel-rt is now available for Red Hat Enterprise Linux
7.

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.

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

Security Fix(es) :

* A race condition flaw was found in the N_HLDC Linux kernel driver
when accessing n_hdlc.tbuf list that can lead to double free. A local,
unprivileged user able to set the HDLC line discipline on the tty
device could use this flaw to increase their privileges on the system.
(CVE-2017-2636, Important)

* A flaw was found in the Linux kernel key management subsystem in
which a local attacker could crash the kernel or corrupt the stack and
additional memory (denial of service) by supplying a specially crafted
RSA key. This flaw panics the machine during the verification of the
RSA key. (CVE-2016-8650, Moderate)

* A flaw was found in the Linux kernel's implementation of setsockopt
for the SO_{SND|RCV}BUFFORCE setsockopt() system call. Users with
non-namespace CAP_NET_ADMIN are able to trigger this call and create a
situation in which the sockets sendbuff data size could be negative.
This could adversely affect memory allocations and create situations
where the system could crash or cause memory corruption.
(CVE-2016-9793, Moderate)

* A flaw was found in the Linux kernel's handling of clearing SELinux
attributes on /proc/pid/attr files. An empty (null) write to this file
can crash the system by causing the system to attempt to access
unmapped kernel memory. (CVE-2017-2618, Moderate)

Red Hat would like to thank Alexander Popov for reporting
CVE-2017-2636 and Ralf Spenneberg for reporting CVE-2016-8650. The
CVE-2017-2618 issue was discovered by Paul Moore (Red Hat
Engineering).

Bug Fix(es) :

* Previously, a cgroups data structure was sometimes corrupted due to
a race condition in the kernel-rt cgroups code. Consequently, several
system tasks were blocked, and the operating system became
unresponsive. This update adds a lock that prevents the race
condition. As a result, the cgroups data structure no longer gets
corrupted and the operating system no longer hangs under the described
circumstances. (BZ#1420784)

* The kernel-rt packages have been upgraded to the 3.10.0-514.16.1
source tree, which provides a number of bug fixes over the previous
version. (BZ#1430749)

See also :

https://www.redhat.com/security/data/cve/CVE-2016-8650.html
https://www.redhat.com/security/data/cve/CVE-2016-9793.html
https://www.redhat.com/security/data/cve/CVE-2017-2618.html
https://www.redhat.com/security/data/cve/CVE-2017-2636.html
http://rhn.redhat.com/errata/RHSA-2017-0931.html

Solution :

Update the affected packages.

Risk factor :

High / CVSS Base Score : 7.2
(CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C)
CVSS Temporal Score : 6.0
(CVSS2#E:F/RL:OF/RC:ND)
Public Exploit Available : true

Family: Red Hat Local Security Checks

Nessus Plugin ID: 99344 ()

Bugtraq ID:

CVE ID: CVE-2016-8650
CVE-2016-9793
CVE-2017-2618
CVE-2017-2636

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