Scientific Linux Security Update : libvirt on SL7.x x86_64
Medium Nessus Plugin ID 80397
SynopsisThe remote Scientific Linux host is missing one or more security updates.
DescriptionIt was found that when the VIR_DOMAIN_XML_MIGRATABLE flag was used, the QEMU driver implementation of the virDomainGetXMLDesc() function could bypass the restrictions of the VIR_DOMAIN_XML_SECURE flag. A remote attacker able to establish a read-only connection to libvirtd could use this flaw to leak certain limited information from the domain XML data. (CVE-2014-7823)
This update also fixes the following bugs :
- In Scientific Linux 6, libvirt relies on the QEMU emulator to supply the error message when an active commit is attempted. However, with Scientific Linux 7, QEMU added support for an active commit, but an additional interaction from libvirt to fully enable active commits is still missing. As a consequence, attempts to perform an active commit caused libvirt to become unresponsive. With this update, libvirt has been fixed to detect an active commit by itself, and now properly declares the feature as unsupported. As a result, libvirt no longer hangs when an active commit is attempted and instead produces an error message.
- Prior to this update, the libvirt API did not properly check whether a Discretionary Access Control (DAC) security label is non-NULL before trying to parse user/group ownership from it. In addition, the DAC security label of a transient domain that had just finished migrating to another host is in some cases NULL. As a consequence, when the virDomainGetBlockInfo API was called on such a domain, the libvirtd daemon sometimes terminated unexpectedly. With this update, libvirt properly checks DAC labels before trying to parse them, and libvirtd thus no longer crashes in the described scenario.
- If a block copy operation was attempted while another block copy was already in progress to an explicit raw destination, libvirt previously stopped regarding the destination as raw. As a consequence, if the qemu.conf file was edited to allow file format probing, triggering the bug could allow a malicious guest to bypass sVirt protection by making libvirt regard the file as non-raw.
With this update, libvirt has been fixed to consistently remember when a block copy destination is raw, and guests can no longer circumvent sVirt protection when the host is configured to allow format probing.
After installing the updated packages, libvirtd will be restarted automatically.
SolutionUpdate the affected packages.