RHSA-2013:0882 - Security Advisory

Topic

Updated kernel packages that fix multiple 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.

Description

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

This update fixes the following security issues:

• A flaw was found in the way the vhost kernel module handled descriptors

that spanned multiple regions. A privileged guest user in a KVM
(Kernel-based Virtual Machine) guest could use this flaw to crash the host
or, potentially, escalate their privileges on the host. (CVE-2013-0311,
Important)

• A flaw was found in the way the KVM subsystem handled guests attempting

to run with the X86_CR4_OSXSAVE CPU feature flag set. On hosts without the
XSAVE CPU feature, a local, unprivileged user could use this flaw to crash
the host system. (The "grep --color xsave /proc/cpuinfo" command can be
used to verify if your system has the XSAVE CPU feature.) (CVE-2012-4461,
Moderate)

• It was found that the default SCSI command filter does not accommodate

commands that overlap across device classes. A privileged guest user could
potentially use this flaw to write arbitrary data to a LUN that is
passed-through as read-only. (CVE-2012-4542, Moderate)

• A use-after-free flaw was found in the tmpfs implementation. A local user

able to mount and unmount a tmpfs file system could use this flaw to cause
a denial of service or, potentially, escalate their privileges.
(CVE-2013-1767, Low)

Red Hat would like to thank Jon Howell for reporting CVE-2012-4461.
CVE-2012-4542 was discovered by Paolo Bonzini of Red Hat.

This update also fixes the following bugs:

• Previously, when open(2) system calls were processed, the GETATTR

routine did not check to see if valid attributes were also returned. As a
result, the open() call succeeded with invalid attributes instead of
failing in such a case. This update adds the missing check, and the open()
call succeeds only when valid attributes are returned. (BZ#960409)

• Previously, the fsync(2) system call incorrectly returned the EIO

(Input/Output) error instead of the ENOSPC (No space left on device) error.
This was due to incorrect error handling in the page cache. This problem
has been fixed and the correct error value is now returned. (BZ#960418)

• In the RPC code, when a network socket backed up due to high network

traffic, a timer was set causing a retransmission, which in turn could
cause an even larger amount of network traffic to be generated. To prevent
this problem, the RPC code now waits for the socket to empty instead of
setting the timer. (BZ#960423)

• This update fixes a number of bugs in the be2iscsi driver for

ServerEngines BladeEngine 2 Open iSCSI devices. (BZ#955502)

Users should 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/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.

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.2 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.2 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.2 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.2 ppc64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.2 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.2 i386
• Red Hat Storage 2.0 x86_64
• Red Hat Gluster Storage Server for On-premise 2.0 x86_64
• Red Hat Storage for Public Cloud (via RHUI) 2.0 x86_64
• Red Hat Enterprise Linux Server - AUS 6.2 x86_64

Fixes

• BZ - 862900 - CVE-2012-4461 kernel: kvm: invalid opcode oops on SET_SREGS with OSXSAVE bit set
• BZ - 875360 - CVE-2012-4542 kernel: block: default SCSI command filter does not accomodate commands overlap across device classes
• BZ - 912905 - CVE-2013-0311 kernel: vhost: fix length for cross region descriptor
• BZ - 915592 - CVE-2013-1767 Kernel: tmpfs: fix use-after-free of mempolicy object

CVEs

• CVE-2012-4461
• CVE-2013-0311
• CVE-2012-4542
• CVE-2013-1767

References

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