RHSA-2015:0008 - Security Advisory

Topic

Updated libvirt packages that fix one security issue and three bugs are now
available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Low security
impact. A Common Vulnerability Scoring System (CVSS) base score, which
gives a detailed severity rating, is available from the CVE link in the
References section.

Description

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 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 issue was discovered by Eric Blake of Red Hat.

This update also fixes the following bugs:

• In Red Hat Enterprise Linux 6, libvirt relies on the QEMU emulator to

supply the error message when an active commit is attempted. However, with
Red Hat Enterprise 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.

Note that the missing libvirt interaction will be added in Red Hat
Enterprise Linux 7.1, adding full support for active commits. (BZ#1150379)

• 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. (BZ#1171124)

• 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. (BZ#1149078)

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.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to use the
Red Hat Network to apply this update are available at
https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.5 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.3 x86_64
• Red Hat Enterprise Linux Server from RHUI 7 x86_64
• Red Hat Enterprise Linux Server - AUS 7.7 x86_64
• Red Hat Enterprise Linux Server - AUS 7.6 x86_64
• Red Hat Enterprise Linux Server - AUS 7.4 x86_64
• Red Hat Enterprise Linux Server - AUS 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 7 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for IBM z Systems 7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.4 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.3 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.5 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.4 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.3 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.6 x86_64
• Red Hat Enterprise Linux Server - TUS 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 7 s390x
• Red Hat Enterprise Linux EUS Compute Node 7.7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.6 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.5 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.4 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 7.3 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, big endian 7 ppc64

Fixes

• BZ - 1150379 - attempts to live snapshot merge (commit) of the active layer hang
• BZ - 1160817 - CVE-2014-7823 libvirt: dumpxml: information leak with migratable flag
• BZ - 1171124 - libvirtd occasionally crashes at the end of migration

CVEs

• CVE-2014-7823

References

• https://access.redhat.com/security/updates/classification/#low