RHSA-2014:0593 - Security Advisory

Topic

Updated kernel packages that fix two security issues and one bug are now
available for Red Hat Enterprise Linux 6.3 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.

Description

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

• A flaw was found in the way the Linux kernel's netfilter connection

tracking implementation for Datagram Congestion Control Protocol (DCCP)
packets used the skb_header_pointer() function. A remote attacker could use
this flaw to send a specially crafted DCCP packet to crash the system or,
potentially, escalate their privileges on the system. (CVE-2014-2523,
Important)

• A flaw was found in the way the handle_rx() function handled large

network packets when mergeable buffers were disabled. A privileged guest
user could use this flaw to crash the host or corrupt QEMU process memory
on the host, which could potentially result in arbitrary code execution on
the host with the privileges of the QEMU process. (CVE-2014-0077, Moderate)

The CVE-2014-0077 issue was discovered by Michael S. Tsirkin of Red Hat.

This update also fixes the following bug:

• Prior to this update, a guest-provided value was used as the head length

of the socket buffer allocated on the host. If the host was under heavy
memory load and the guest-provided value was too large, the allocation
could have failed, resulting in stalls and packet drops in the guest's Tx
path. With this update, the guest-provided value has been limited to a
reasonable size so that socket buffer allocations on the host succeed
regardless of the memory load on the host, and guests can send packets
without experiencing packet drops or stalls. (BZ#1092350)

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.

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/site/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.

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.3 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.3 ppc64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 i386
• Red Hat Enterprise Linux EUS Compute Node 6.3 x86_64

Fixes

• BZ - 1064440 - CVE-2014-0077 kernel: vhost-net: insufficiency in handling of big packets in handle_rx()
• BZ - 1077343 - CVE-2014-2523 kernel: netfilter: nf_conntrack_dccp: incorrect skb_header_pointer API usages

CVEs

• CVE-2014-2523
• CVE-2014-0077

References

• https://access.redhat.com/security/updates/classification/#important