RHSA-2012:0051 - Security Advisory

Topic

Updated kvm packages that fix two security issues are now available for
Red Hat Enterprise Linux 5.

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

KVM (Kernel-based Virtual Machine) is a full virtualization solution for
Linux on AMD64 and Intel 64 systems. KVM is a Linux kernel module built for
the standard Red Hat Enterprise Linux kernel.

A heap overflow flaw was found in the way QEMU-KVM emulated the e1000
network interface card. A privileged guest user in a virtual machine whose
network interface is configured to use the e1000 emulated driver could use
this flaw to crash the host or, possibly, escalate their privileges on the
host. (CVE-2012-0029)

A flaw was found in the way the KVM subsystem of a Linux kernel handled PIT
(Programmable Interval Timer) IRQs (interrupt requests) when there was no
virtual interrupt controller set up. A malicious user in the kvm group on
the host could force this situation to occur, resulting in the host
crashing. (CVE-2011-4622)

Red Hat would like to thank Nicolae Mogoreanu for reporting CVE-2012-0029.

All KVM users should upgrade to these updated packages, which contain
backported patches to correct these issues. Note: The procedure in the
Solution section must be performed before this update will 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/kb/docs/DOC-11259

The following procedure must be performed before this update will take
effect:

1) Stop all KVM guest virtual machines.

2) Either reboot the hypervisor machine or, as the root user, remove (using
"modprobe -r [module]") and reload (using "modprobe [module]") all of the
following modules which are currently running (determined using "lsmod"):
kvm, ksm, kvm-intel or kvm-amd.

3) Restart the KVM guest virtual machines.

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Workstation 5 x86_64

Fixes

• BZ - 769721 - CVE-2011-4622 kernel: kvm: pit timer with no irqchip crashes the system
• BZ - 772075 - CVE-2012-0029 qemu-kvm: e1000: process_tx_desc legacy mode packets heap overflow

CVEs

• CVE-2012-0029
• CVE-2011-4622

References

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