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. 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. * 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. * 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. 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.