libvirt security update

CentOS Errata and Security Advisory CESA-2014:0560

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 remote management of virtualized
systems.

It was found that libvirt passes the XML_PARSE_NOENT flag when parsing XML
documents using the libxml2 library, in which case all XML entities in the
parsed documents are expanded. A user able to force libvirtd to parse an
XML document with an entity pointing to a special file that blocks on read
access could use this flaw to cause libvirtd to hang indefinitely,
resulting in a denial of service on the system. (CVE-2014-0179)

Red Hat would like to thank the upstream Libvirt project for reporting this
issue. Upstream acknowledges Daniel P. Berrange and Richard Jones as the
original reporters.

This update also fixes the following bugs:

• When hot unplugging a virtual CPU (vCPU), libvirt kept a pointer to
  already freed memory if the vCPU was pinned to a host CPU. Consequently,
  when reading the CPU pinning information, libvirt terminated unexpectedly
  due to an attempt to access this memory. This update ensures that libvirt
  releases the pointer to the previously allocated memory when a vCPU is
  being hot unplugged, and it no longer crashes in this situation.
  (BZ#1091206)

• Previously, libvirt passed an incorrect argument to the “tc” command when
  setting quality of service (QoS) on a network interface controller (NIC).
  As a consequence, QoS was applied only to IP traffic. With this update,
  libvirt constructs the “tc” command correctly so that QoS is applied to all
  traffic as expected. (BZ#1096806)

• When using the sanlock daemon for managing access to shared storage,
  libvirt expected all QEMU domains to be registered with sanlock. However,
  if a QEMU domain was started prior to enabling sanlock, the domain was not
  registered with sanlock. Consequently, migration of a virtual machine (VM)
  from such a QEMU domain failed with a libvirt error. With this update,
  libvirt verifies whether a QEMU domain process is registered with sanlock
  before it starts working with the domain, ensuring that migration of
  virtual machines works as expected. (BZ#1097227)

All libvirt users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. After installing the
updated packages, libvirtd will be restarted automatically.

Merged security bulletin from advisories:
https://lists.centos.org/pipermail/centos-announce/2014-May/082484.html

Affected packages:
libvirt
libvirt-client
libvirt-devel
libvirt-lock-sanlock
libvirt-python

Upstream details at:
https://access.redhat.com/errata/RHSA-2014:0560