(RHSA-2011:1197) Moderate: libvirt security and bug fix update

The libvirt library is a C API for managing and interacting with the
virtualization capabilities of Linux and other operating systems. In
addition, libvirt provides tools for remotely managing virtualized systems.

An integer overflow flaw was found in libvirtd’s RPC call handling. An
attacker able to establish read-only connections to libvirtd could trigger
this flaw by calling virDomainGetVcpus() with specially-crafted parameters,
causing libvirtd to crash. (CVE-2011-2511)

This update also fixes the following bugs:

• Previously, when the “virsh vol-create-from” command was run on an LVM
  (Logical Volume Manager) storage pool, performance of the command was very
  low and the operation consumed an excessive amount of time. This bug has
  been fixed in the virStorageVolCreateXMLFrom() function, and the
  performance problem of the command no longer occurs.

• Due to a regression, libvirt used undocumented command line options,
  instead of the recommended ones. Consequently, the qemu-img utility used an
  invalid argument while creating an encrypted volume, and the process
  eventually failed. With this update, the bug in the backing format of the
  storage back end has been fixed, and encrypted volumes can now be created
  as expected. (BZ#726617)

• Due to a bug in the qemuAuditDisk() function, hot unplug failures were
  never audited, and a hot unplug success was audited as a failure. This bug
  has been fixed, and auditing of disk hot unplug operations now works as
  expected. (BZ#728516)

• Previously, when a debug process was being activated, the act of
  preparing a debug message ended up with dereferencing a UUID (universally
  unique identifier) prior to the NULL argument check. Consequently, an API
  running the debug process sometimes terminated with a segmentation fault.
  With this update, a patch has been provided to address this issue, and the
  crashes no longer occur in the described scenario. (BZ#728546)

• The libvirt library uses the “boot=on” option to mark which disk is
  bootable but it only uses that option if Qemu advertises its support. The
  qemu-kvm utility in Red Hat Enterprise Linux 6.1 removed support for that
  option and libvirt could not use it. As a consequence, when an IDE disk was
  added as the second storage with a virtio disk being set up as the first
  one by default, the operating system tried to boot from the IDE disk rather
  than the virtio disk and either failed to boot with the “No bootable disk”
  error message returned, or the system booted whatever operating system was
  on the IDE disk. With this update, the boot configuration is translated
  into bootindex, which provides control over which device is used for
  booting a guest operating system, thus fixing this bug.

All users of libvirt are advised to upgrade to these updated packages,
which contain backported patches to correct these issues. After installing
the updated packages, libvirtd must be restarted (“service libvirtd
restart”) for this update to take effect.