RHEL 7 : kernel-rt (RHSA-2015:2411)

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Synopsis :

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

Description :

Updated kernel-rt packages that fix multiple security issues, several
bugs, and add various enhancements are now available for Red Hat
Enterprise Linux 7.

Red Hat Product Security has rated this update as having Important
security impact. Common Vulnerability Scoring System (CVSS) base
scores, which give detailed severity ratings, are available for each
vulnerability from the CVE links in the References section.

The kernel-rt packages contain the Linux kernel, the core of any Linux
operating 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 the destination was outside of a bind mount. A privileged
user inside a container could use this flaw to escape the bind mount
and, potentially, escalate their privileges on the system.
(CVE-2015-2925, 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
were later used for permission checking before inserting the object
into a globally visible list. A local, unprivileged user could
potentially use this flaw to elevate their privileges on the system.
(CVE-2015-7613, Important)

* It was found that the Linux kernel memory resource controller's
(memcg) handling of OOM (out of memory) conditions could lead to
deadlocks. An attacker able to continuously spawn new processes within
a single memory-constrained cgroup during an OOM event could use this
flaw to lock up the system. (CVE-2014-8171, Moderate)

* A race condition flaw was found between the chown and execve system
calls. When changing the owner of a setuid user binary to root, the
race condition could momentarily make the binary setuid root. A local,
unprivileged user could potentially use this flaw to escalate their
privileges on the system. (CVE-2015-3339, Moderate)

* A flaw was discovered in the way the Linux kernel's TTY subsystem
handled the tty shutdown phase. A local, unprivileged user could use
this flaw to cause a denial of service on the system by holding a
reference to the ldisc lock during tty shutdown, causing a deadlock.
(CVE-2015-4170, Moderate)

* A NULL pointer dereference flaw was found in the SCTP
implementation. A local user could use this flaw to cause a denial of
service on the system by triggering a kernel panic when creating
multiple sockets in parallel while the system did not have the SCTP
module loaded. (CVE-2015-5283, Moderate)

* A flaw was found in the way the Linux kernel's Crypto subsystem
handled automatic loading of kernel modules. A local user could use
this flaw to load any installed kernel module, and thus increase the
attack surface of the running kernel. (CVE-2013-7421, CVE-2014-9644,
Low)

* An information leak flaw was found in the way the Linux kernel
changed certain segment registers and thread-local storage (TLS)
during a context switch. A local, unprivileged user could use this
flaw to leak the user space TLS base address of an arbitrary process.
(CVE-2014-9419, Low)

* A flaw was found in the way the Linux kernel handled the securelevel
functionality after performing a kexec operation. A local attacker
could use this flaw to bypass the security mechanism of the
securelevel/secureboot combination. (CVE-2015-7837, Low)

Red Hat would like to thank Linn Crosetto of HP for reporting the
CVE-2015-7837 issue. The CVE-2015-5283 issue was discovered by Ji
Jianwen from Red Hat engineering.

The kernel-rt packages have been upgraded to version
3.10.0-326.rt56.204, which provides a number of bug fixes and
enhancements. (BZ#1201915, BZ#1211724)

This update also fixes several bugs and adds multiple enhancements.
Refer to the following Red Hat Knowledgebase article for information
on the most significant of these changes :

https://access.redhat.com/articles/2055783

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.

See also :

https://www.redhat.com/security/data/cve/CVE-2013-7421.html
https://www.redhat.com/security/data/cve/CVE-2014-8171.html
https://www.redhat.com/security/data/cve/CVE-2014-9419.html
https://www.redhat.com/security/data/cve/CVE-2014-9644.html
https://www.redhat.com/security/data/cve/CVE-2015-2925.html
https://www.redhat.com/security/data/cve/CVE-2015-3339.html
https://www.redhat.com/security/data/cve/CVE-2015-4170.html
https://www.redhat.com/security/data/cve/CVE-2015-5283.html
https://www.redhat.com/security/data/cve/CVE-2015-7613.html
https://www.redhat.com/security/data/cve/CVE-2015-7837.html
https://access.redhat.com/articles/2055783
http://rhn.redhat.com/errata/RHSA-2015-2411.html

Solution :

Update the affected packages.

Risk factor :

Medium / CVSS Base Score : 6.9
(CVSS2#AV:L/AC:M/Au:N/C:C/I:C/A:C)
CVSS Temporal Score : 5.1
(CVSS2#E:U/RL:OF/RC:C)
Public Exploit Available : false

Family: Red Hat Local Security Checks

Nessus Plugin ID: 88571 ()

Bugtraq ID:

CVE ID: CVE-2013-7421
CVE-2014-8171
CVE-2014-9419
CVE-2014-9644
CVE-2015-2925
CVE-2015-3339
CVE-2015-4170
CVE-2015-5283
CVE-2015-7613
CVE-2015-7837

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