Issued:
2012-09-05
Updated:
2012-09-05

RHSA-2012:1234 - Important: qemu-kvm security update

Synopsis

Important: qemu-kvm security update

Type/Severity

Security Advisory Important

Topic

Updated qemu-kvm packages that fix one security issue are now available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having important 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.

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.

A flaw was found in the way QEMU handled VT100 terminal escape sequences when emulating certain character devices. A guest user with privileges to write to a character device that is emulated on the host using a virtual console back-end could use this flaw to crash the qemu-kvm process on the host or, possibly, escalate their privileges on the host. (CVE-2012-3515)

This flaw did not affect the default use of KVM. Affected configurations were:

  • When guests were started from the command line ("/usr/libexec/qemu-kvm") without the "-nodefaults" option, and also without specifying a serial or parallel device, or a virtio-console device, that specifically does not use a virtual console (vc) back-end. (Note that Red Hat does not support invoking "qemu-kvm" from the command line without "-nodefaults" on Red Hat Enterprise Linux 6.)

  • Guests that were managed via libvirt, such as when using Virtual Machine Manager (virt-manager), but that have a serial or parallel device, or a virtio-console device, that uses a virtual console back-end. By default, guests managed via libvirt will not use a virtual console back-end for such devices.

Red Hat would like to thank the Xen project for reporting this issue.

All users of qemu-kvm should upgrade to these updated packages, which resolve this issue. 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 https://access.redhat.com/knowledge/articles/11258

Affected Products

ProductVersionArch
Red Hat Enterprise Linux for x86_64 - Extended Update Support6.3x86_64
Red Hat Enterprise Linux for Scientific Computing6x86_64
Red Hat Enterprise Linux Workstation6x86_64
Red Hat Enterprise Linux Server6x86_64
Red Hat Enterprise Linux Server from RHUI6x86_64
Red Hat Enterprise Linux Server - Extended Update Support from RHUI6.3x86_64
Red Hat Enterprise Linux Server - Extended Life Cycle Support6x86_64
Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension6x86_64
Red Hat Enterprise Linux Desktop6x86_64

Updated Packages

  • qemu-kvm-debuginfo-0.12.1.2-2.295.el6_3.2.x86_64.rpm
  • qemu-kvm-0.12.1.2-2.295.el6_3.2.src.rpm
  • qemu-kvm-0.12.1.2-2.295.el6_3.2.x86_64.rpm
  • qemu-guest-agent-0.12.1.2-2.295.el6_3.2.x86_64.rpm
  • qemu-kvm-tools-0.12.1.2-2.295.el6_3.2.x86_64.rpm
  • qemu-img-0.12.1.2-2.295.el6_3.2.x86_64.rpm

Fixes

CVEs

References

Additional information