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

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.