[arch-security] [Arch Linux Security Advisory ASA-201409-5] libvirt: out-of-bounds read access

[Levente Polyak]

Arch Linux Security Advisory ASA-201409-5
=========================================

Severity: Medium
Date    : 2014-09-29
CVE-ID  : CVE-3633
Package : libvirt
Type    : out-of-bounds read access
Remote  : Yes
Link    : https://wiki.archlinux.org/index.php/CVE-2014

Summary
=======

The package libvirt before version 1.2.8-2 is
vulnerable to an out-of-bounds read access in qemuDomainGetBlockIoTune()..

Resolution
==========

Upgrade to 1.2.8-2.

# pacman -Syu "libvirt>=1.2.8-2"

The problem has been fixed upstream [0] but no release is available yet.

Workaround
==========

The out-of-bounds access is only possible on domains that have had disks
hot-plugged or removed from the live image without also updating the
persistent definition to match; keeping the two definitions matched or
using only transient domains will avoid the problem. Denying access to
the readonly libvirt socket will avoid the potential for a denial of
service attack, but will not prevent the out-of-bounds access from
causing a crash for a privileged client, although such a crash is no
longer a security problem.

Description
===========

Luyao Huang of Red Hat found that the qemu implementation of
virDomainGetBlockIoTune computed an index into the array of disks
for the live definition, then used it as the index into the array of
disks for the persistent definition, which could result into an
out-of-bounds read access in qemuDomainGetBlockIoTune().

Impact
======

A remote attacker able to establish a read-only connection to
libvirtd could use this flaw to crash libvirtd or, potentially,
leak memory from the libvirtd process.

References
==========

[0]
http://libvirt.org/git/?p=libvirt.git;a=commit;h=3e745e8f775dfe6f64f18b5c2fe4791b35d3546b
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3633
http://security.libvirt.org/2014/0004.html
https://bugs.archlinux.org/task/42159