RHEL 6 : kernel (RHSA-2012:1129)

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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
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 packages contain the Linux kernel, the core of any Linux
operating system.

This update fixes the following security issues :

* A NULL pointer dereference flaw was found in the nf_ct_frag6_reasm()
function in the Linux kernel's netfilter IPv6 connection tracking
implementation. A remote attacker could use this flaw to send
specially crafted packets to a target system that is using IPv6 and
also has the nf_conntrack_ipv6 kernel module loaded, causing it to
crash. (CVE-2012-2744, Important)

* A flaw was found in the way the Linux kernel's Event Poll (epoll)
subsystem handled large, nested epoll structures. A local,
unprivileged user could use this flaw to cause a denial of service.
(CVE-2011-1083, Moderate)

Red Hat would like to thank an anonymous contributor working with the
Beyond Security SecuriTeam Secure Disclosure program for reporting
CVE-2012-2744, and Nelson Elhage for reporting CVE-2011-1083.

This update also fixes the following bugs :

* Attempting to turn on Data Center Bridging (DCB) on a port connected
to a non-DCB switch port caused the system to become unresponsive or
even terminate. This was because napi_poll routines in the ixgbe
driver did not end the NAPI when data processing was complete. With
this update, the ixgbe napi_poll routines have been fixed so that they
now call the napi_complete() function when data processing has
finished. This ensures that the NAPI is correctly disabled, and thus
prevents possible hangs and crashes in this scenario. (BZ#814454)

* If a new file was created on a Network File System version 4 (NFSv4)
share, the ownership was set to nfsnobody (-2) until it was possible
to upcall to the idmapper. As a consequence, subsequent file system
operations could incorrectly use '-2' for the user and group IDs for
the given file, causing certain operations to fail. In reported cases,
this issue also caused 'Viminfo file is not writable' errors for users
running Vim with files on an NFSv4 share. (BZ#820962)

* Previously, the size of the multicast IGMP (Internet Group
Management Protocol) snooping hash table for a bridge was limited to
256 entries even though the maximum is 512. This was due to the hash
table size being incorrectly compared to the maximum hash table size,
hash_max, and the following message could have been produced by the
kernel :

Multicast hash table maximum reached, disabling snooping: vnet1, 512

With this update, the hash table value is correctly compared to the
hash_max value, and the error message no longer occurs under these
circumstances. (BZ#840021)

Users should upgrade to these updated packages, which contain
backported patches to resolve these issues. The system must be
rebooted for this update to take effect.

See also :

https://www.redhat.com/security/data/cve/CVE-2011-1083.html
https://www.redhat.com/security/data/cve/CVE-2012-2744.html
http://rhn.redhat.com/errata/RHSA-2012-1129.html

Solution :

Update the affected packages.

Risk factor :

High / CVSS Base Score : 7.8
(CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C)

Family: Red Hat Local Security Checks

Nessus Plugin ID: 64050 ()

Bugtraq ID:

CVE ID: CVE-2011-1083
CVE-2012-2744