Issued:

2011-07-05

Updated:

2011-07-05

RHSA-2011:0919 - Important: qemu-kvm security and bug fix update

Synopsis

Important: qemu-kvm security and bug fix update

Type/Severity

Security Advisory Important

Topic

Updated qemu-kvm packages that fix two security issues and one bug are now available for Red Hat Enterprise Linux 6.

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. qemu-kvm is the user-space component for running virtual machines using KVM.

It was found that the virtio subsystem in qemu-kvm did not properly validate virtqueue in and out requests from the guest. A privileged guest user could use this flaw to trigger a buffer overflow, allowing them to crash the guest (denial of service) or, possibly, escalate their privileges on the host. (CVE-2011-2212)

It was found that the virtio_queue_notify() function in qemu-kvm did not perform sufficient input validation on the value later used as an index into the array of virtqueues. An unprivileged guest user could use this flaw to crash the guest (denial of service) or, possibly, escalate their privileges on the host. (CVE-2011-2512)

Red Hat would like to thank Nelson Elhage for reporting CVE-2011-2212.

This update also fixes the following bug:

• A bug was found in the way vhost (in qemu-kvm) set up mappings with the host kernel's vhost module. This could result in the host kernel's vhost module not having a complete view of a guest system's memory, if that guest had more than 4 GB of memory. Consequently, hot plugging a vhost-net network device and restarting the guest may have resulted in that device no longer working. (BZ#701771)

All users of qemu-kvm should upgrade to these updated packages, which contain backported patches to resolve these issues. After installing this update, shut down all running virtual machines. Once all virtual machines have shut down, start them again 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 This content is not included.https://access.redhat.com/kb/docs/DOC-11259

Affected Products

Updated Packages

• qemu-kvm-0.12.1.2-2.160.el6_1.2.src.rpm
• qemu-kvm-debuginfo-0.12.1.2-2.160.el6_1.2.x86_64.rpm
• qemu-kvm-0.12.1.2-2.160.el6_1.2.x86_64.rpm
• qemu-kvm-tools-0.12.1.2-2.160.el6_1.2.x86_64.rpm
• qemu-img-0.12.1.2-2.160.el6_1.2.x86_64.rpm

Fixes

• This content is not included.BZ - 713589
• This content is not included.BZ - 717399

CVEs

• CVE-2011-2512
• CVE-2011-2212

References

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

Additional information

• The Red Hat security contact is This content is not included.secalert@redhat.com. More contact details at https://access.redhat.com/security/team/contact/.
• Offline Security Data data is available for integration with other systems. See Offline Security Data API to get started.