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AUSCERT External Security Bulletin Redistribution
Moderate: kvm security and bug fix update
22 February 2012
AusCERT Security Bulletin Summary
Publisher: Red Hat
Operating System: Red Hat Enterprise Linux Server 5
Red Hat Enterprise Linux WS/Desktop 5
Impact/Access: Denial of Service -- Existing Account
CVE Names: CVE-2011-4347
Comment: This advisory references vulnerabilities in products which run on
platforms other than Red Hat. It is recommended that administrators
running kvm check for an updated version of the software for their
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Red Hat Security Advisory
Synopsis: Moderate: kvm security and bug fix update
Advisory ID: RHSA-2012:0149-03
Product: Red Hat Enterprise Linux
Advisory URL: https://rhn.redhat.com/errata/RHSA-2012-0149.html
Issue date: 2012-02-21
CVE Names: CVE-2011-4347
Updated kvm packages that fix one security issue and several bugs are now
available for Red Hat Enterprise Linux 5.
The Red Hat Security Response Team has rated this update as having moderate
security impact. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available from the CVE link 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.
It was found that the kvm_vm_ioctl_assign_device() function in the KVM
subsystem of a Linux kernel did not check if the user requesting device
assignment was privileged or not. A member of the kvm group on the host
could assign unused PCI devices, or even devices that were in use and
whose resources were not properly claimed by the respective drivers, which
could result in the host crashing. (CVE-2011-4347)
Red Hat would like to thank Sasha Levin for reporting this issue.
These updated kvm packages include several bug fixes. Space precludes
documenting all of these changes in this advisory. Users are directed to
the Red Hat Enterprise Linux 5.8 Technical Notes, linked to in the
References, for information on the most significant of these changes.
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/):
701616 - limitation on max number of assigned devices does not take effect if hot-plug pci devices
703335 - KVM guest clocks jump forward one hour on reboot
703446 - Failed to ping guest after MTU is changed
704081 - mouse responds very slowly with huge memory
725876 - RTC interrupt problems with RHEL5 qemu/kvm (0.10 based) on 2.6.38+ guest kernels.
753860 - Fix kvm userspace compilation on RHEL-5 to match the kernel changes
756084 - CVE-2011-4347 kernel: kvm: device assignment DoS
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 <email@example.com>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2012 Red Hat, Inc.
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