RHEL 7 : kernel (RHSA-2016:1395)

This script is Copyright (C) 2016-2017 Tenable Network Security, Inc.


Synopsis :

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

Description :

Updated kernel packages that fix one security issue and several bugs
are now available for Red Hat Enterprise Linux 7 Extended Update
Support.

Red Hat Product Security has rated this update as having Moderate
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 packages contain the Linux kernel, the core of any Linux
operating system.

Security fix :

* 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 denial of service on the system by holding a
reference to the ldisc lock during tty shutdown, causing a deadlock.
(CVE-2015-4170, Moderate)

This update also fixes the following bugs :

* When Small Computer System Interface (SCSI) devices were removed or
deleted, a system crash could occur due to a race condition between
listing all SCSI devices and SCSI device removal. The provided patch
ensures that the starting node for the klist_iter_init_node() function
is actually a member of the list before using it. As a result, a
system crash no longer occurs in the described scenario. (BZ#1333402)

* When creating Virtual Functions (VF) on the ixgbe driver, the Media
Access Control (MAC) address for each VF could be random if not
explicitly set. When generating a random MAC address, it was possible
to set the address to zero. As a consequence, transmitted packets were
discarded without being sent, and the user was not able to access the
network. The provided patchset ensures that the VFs always end up with
valid MAC addresses. As a result, packets are now transmitted as
expected, and the user is able to access the network. (BZ#1335405)

* Under significant load, some applications such as logshifter could
generate bursts of log messages too large for the system logger to
spool. Due to a race condition, log messages from that application
could then be lost even after the log volume dropped to manageable
levels. This update fixes the kernel mechanism used to notify the
transmitter end of the socket used by the system logger that more
space is available on the receiver side, removing a race condition
which previously caused the sender to stop transmitting new messages
and allowing all log messages to be processed correctly. (BZ#1337602)

* When a USB serial driver was trying to acquire a line-discipline
reference, a lockdep warning could occur due to the tty ldisc
semaphore that was not fully initialized. With this update, a set of
patches has been backported from upstream that fix this bug and no
warnings occur in the aforementioned scenario. (BZ#1343554)

All kernel users are advised to upgrade to these updated packages,
which contain backported patches to correct these issues. The system
must be rebooted for this update to take effect.

See also :

https://www.redhat.com/security/data/cve/CVE-2015-4170.html
http://rhn.redhat.com/errata/RHSA-2016-1395.html

Solution :

Update the affected packages.

Risk factor :

Medium / CVSS Base Score : 4.7
(CVSS2#AV:L/AC:M/Au:N/C:N/I:N/A:C)
CVSS Temporal Score : 3.5
(CVSS2#E:U/RL:OF/RC:C)
Public Exploit Available : false

Family: Red Hat Local Security Checks

Nessus Plugin ID: 92029 ()

Bugtraq ID:

CVE ID: CVE-2015-4170

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