(RHSA-2014:0914) 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 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 file could use this flaw to read
the contents of that file; parsing an XML document with an entity pointing
to a special file that blocks on read access could 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:

• A previous update of the libvirt package introduced an error; a
  SIG_SETMASK argument was incorrectly replaced by a SIG_BLOCK argument after
  the poll() system call. Consequently, the SIGCHLD signal could be
  permanently blocked, which caused signal masks to not return to their
  original values and defunct processes to be generated. With this update,
  the original signal masks are restored and defunct processes are no longer
  generated. (BZ#1112689)

• An attempt to start a domain that did not exist caused network filters to
  be locked for read-only access. As a consequence, when trying to gain
  read-write access, a deadlock occurred. This update applies a patch to fix
  this bug and an attempt to start a non-existent domain no longer causes a
  deadlock in the described scenario. (BZ#1112690)

• Previously, the libvirtd daemon was binding only to addresses that were
  configured on certain network interfaces. When libvirtd started before the
  IPv4 addresses had been configured, libvirtd listened only on the IPv6
  addresses. The daemon has been modified to not require an address to be
  configured when binding to a wildcard address, such as “0.0.0.0” or “::”.
  As a result, libvirtd binds to both IPv4 and IPv6 addresses as expected.
  (BZ#1112692)

Users of libvirt are advised to upgrade to these updated packages, which
fix these bugs. After installing the updated packages, libvirtd will be
restarted automatically.