7.8 - RHSA-2012:1129

Problem 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.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Server EUS (v. 6.2) - i386, noarch, ppc64, s390x, x86_64 Red Hat Enterprise Linux Server Optional EUS (v. 6.2) - i386, ppc64, s390x, x86_64

3. Description:

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.

4. Solution:

Before applying this update, make sure all previously-released errata relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at https://access.redhat.com/knowledge/articles/11258

To install kernel packages manually, use "rpm -ivh [package]". Do not use "rpm -Uvh" as that will remove the running kernel binaries from your system. You may use "rpm -e" to remove old kernels after determining that the new kernel functions properly on your system.

5. Bugs fixed (http://bugzilla.redhat.com/):

681578 - CVE-2011-1083 kernel: excessive in kernel CPU consumption when creating large nested epoll structures 833402 - CVE-2012-2744 kernel: netfilter: null pointer dereference in nf_ct_frag6_reasm()