(Red Hat Issues Fix) KVM PIT IRQ Bug Lets Local Users Deny Service
SecurityTracker Alert ID: 1026562|
SecurityTracker URL: http://securitytracker.com/id/1026562
(Links to External Site)
Date: Jan 23 2012
Denial of service via local system|
Fix Available: Yes Vendor Confirmed: Yes |
A vulnerability was reported in KVM. A local user on the host system can cause denial of service conditions.|
The system does not properly handle Programmable Interval Timer (PIT) IRQs when a virtual interrupt controller has not been set up. A local user in the kvm group on the host system can cause the host system to crash.
A local user in the kvm group on the host system can cause the host system to crash.|
Red Hat has issued a fix.|
The Red Hat advisory is available at:
Vendor URL: linux-kvm.org/ (Links to External Site)
|Underlying OS: Linux (Red Hat Enterprise)|
|Underlying OS Comments: 5|
This archive entry is a follow-up to the message listed below.|
Source Message Contents
Subject: [RHSA-2012:0051-01] Important: kvm security update|
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Red Hat Security Advisory
Synopsis: Important: kvm security update
Advisory ID: RHSA-2012:0051-01
Product: Red Hat Enterprise Linux
Advisory URL: https://rhn.redhat.com/errata/RHSA-2012-0051.html
Issue date: 2012-01-23
CVE Names: CVE-2011-4622 CVE-2012-0029
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.
2. Relevant releases/architectures:
RHEL Desktop Multi OS (v. 5 client) - x86_64
RHEL Virtualization (v. 5 server) - x86_64
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
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
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.
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
The following procedure must be performed before this update will take
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.
5. Bugs fixed (http://bugzilla.redhat.com/):
769721 - CVE-2011-4622 kernel: kvm: pit timer with no irqchip crashes the system
772075 - CVE-2012-0029 qemu-kvm: e1000: process_tx_desc legacy mode packets heap overflow
6. Package List:
RHEL Desktop Multi OS (v. 5 client):
RHEL Virtualization (v. 5 server):
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
The Red Hat security contact is <firstname.lastname@example.org>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2012 Red Hat, Inc.
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