RHSA-2013:0831 - Security Advisory

Topic

Updated libvirt packages that fix one security issue and two bugs are now
available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate
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 libvirtd leaked file descriptors when listing all volumes
for a particular pool. A remote attacker able to establish a read-only
connection to libvirtd could use this flaw to cause libvirtd to consume all
available file descriptors, preventing other users from using libvirtd
services (such as starting a new guest) until libvirtd is restarted.
(CVE-2013-1962)

Red Hat would like to thank Edoardo Comar of IBM for reporting this issue.

This update also fixes the following bugs:

• Previously, libvirt made control group (cgroup) requests on files that

it should not have. With older kernels, such nonsensical cgroup requests
were ignored; however, newer kernels are stricter, resulting in libvirt
logging spurious warnings and failures to the libvirtd and audit logs. The
audit log failures displayed by the ausearch tool were similar to the
following:

root [date] - failed cgroup allow path rw /dev/kqemu

With this update, libvirt no longer attempts the nonsensical cgroup
actions, leaving only valid attempts in the libvirtd and audit logs (making
it easier to search for real cases of failure). (BZ#958837)

• Previously, libvirt used the wrong variable when constructing audit

messages. This led to invalid audit messages, causing ausearch to format
certain entries as having "path=(null)" instead of the correct path. This
could prevent ausearch from locating events related to cgroup device ACL
modifications for guests managed by libvirt. With this update, the audit
messages are generated correctly, preventing loss of audit coverage.
(BZ#958839)

All users of libvirt 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/knowledge/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.4 i386
• Red Hat Enterprise Linux Server - AUS 6.4 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.4 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.4 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Virtualization 3 for RHEL 6 x86_64
• Red Hat Gluster Storage Server for On-premise 2.1 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.4 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.4 i386
• Red Hat Storage for Public Cloud (via RHUI) 2.1 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

• BZ - 953107 - CVE-2013-1962 libvirt: DoS (max count of open files exhaustion) due sockets leak in the storage pool
• BZ - 958837 - libvirt spams audit log with unneeded failures
• BZ - 958839 - Cgroup audit events with path are not escaped

CVEs

• CVE-2013-1962

References

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