RHEL 6 : kernel (RHSA-2012:1541)

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Synopsis :

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

Description :

Updated kernel packages that fix two security issues and several bugs
are now available for Red Hat Enterprise Linux 6.2 Extended Update
Support.

The Red Hat Security Response Team 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.

These packages contain the Linux kernel.

Security fixes :

* A malicious NFSv4 server could return a crafted reply to a GETACL
request, causing a denial of service on the client. (CVE-2011-4131,
Moderate)

* A flaw in the dl2k driver could allow a local, unprivileged user to
issue potentially harmful IOCTLs, possibly causing Ethernet adapters
using the driver to malfunction (such as losing network connectivity).
(CVE-2012-2313, Low)

Red Hat would like to thank Andy Adamson for reporting CVE-2011-4131,
and Stephan Mueller for reporting CVE-2012-2313.

Bug fixes :

* A kernel oops occurred in the nf_nat code when a bogus pointer was
dereferenced in the nf_conn_nat structure. Consequently, if Source
Network Address Translation (SNAT) was performed, incorrect
information could be received by other CTS (Clear to Send) signals. A
conntrack entry is now placed in the source hash after SNAT has been
completed, which prevents the described problems. (BZ#865715)

* Previously, the ixgbe_setup_tc() function was called recursively
when the set_state() CEE (Convergence Enhanced Ethernet) API routine
was called in IEEE DCBX (Data Center Bridging eXchange) mode. This is
considered unsafe according to the IEEE standards. With this update,
the ixgbe driver has been modified to no longer call the set_state()
routine in IEEE DCBX mode. The driver now calls routines of the PFC
(Priority-based Flow Control) and ETS (Enhanced Transmission
Selection) extensions instead of the CEE extension routines in IEEE
DCBX mode. (BZ#867859)

* A Symmetric Multi Processing (SMP) race condition between the
munmap() and exit() function could lead to false-positive triggering
of the BUG_ON() macro if Transparent Huge Pages (THP) were enabled.
This update fixes the race condition, which avoids false-positive
triggering of the BUG_ON() macro in this scenario. (BZ#875121)

* The kernel allows high priority real time tasks, such as tasks
scheduled with the SCHED_FIFO policy, to be throttled. Previously, the
CPU stop tasks were scheduled as high priority real time tasks and
could be thus throttled accordingly. However, the replenishment timer,
which is responsible for clearing a throttle flag on tasks, could be
pending on the just disabled CPU. This could lead to the situation
that the throttled tasks were never scheduled to run. Consequently, if
any of such tasks was needed to complete the CPU disabling, the system
became unresponsive. This update introduces a new scheduler class,
which gives a task the highest possible system priority and such a
task cannot be throttled. The stop-task scheduling class is now used
for the CPU stop tasks, and the system shutdown completes as expected
in the scenario described. (BZ#876078)

* Previously, XFS log buffers were handled incorrectly so that XFS
could, in certain circumstances, incorrectly read metadata from the
journal during XFS log recovery. As a consequence, XFS log recovery
terminated with an error message and prevented the file system from
being mounted. This problem could result in a loss of data if the user
forcibly emptied the log to allow the file system to be mounted. This
update ensures that metadata is read correctly from the log and
journal recovery thus completes successfully, and the file system
mounts as expected. (BZ#876498)

* Previously, kernel was allowed to reduce the number of unnecessary
commit calls by skipping the commit when there was a large number of
outstanding pages being written. However, a test on the number of
commits (ncommit) did not properly handle the edge case when ncommit
was zero. Consequently, inodes sometimes remained on the sb->s_dirty
list and could not be freed by the inode cache shrinker. As a result,
the nfs_inode_cache structure grew very large over time. With this
update, the call to the nfs_write_inode() function is immediately
returned when commit == 0, thus fixing this bug. (BZ#877394)

See also :

https://www.redhat.com/security/data/cve/CVE-2011-4131.html
https://www.redhat.com/security/data/cve/CVE-2012-2313.html
http://rhn.redhat.com/errata/RHSA-2012-1541.html

Solution :

Update the affected packages.

Risk factor :

Medium / CVSS Base Score : 4.6
(CVSS2#AV:A/AC:H/Au:N/C:N/I:N/A:C)
CVSS Temporal Score : 4.0
(CVSS2#E:ND/RL:OF/RC:C)
Public Exploit Available : true

Family: Red Hat Local Security Checks

Nessus Plugin ID: 64068 ()

Bugtraq ID: 50655
53965

CVE ID: CVE-2011-4131
CVE-2012-2313