Moderate: qemu-kvm (SL6)

Synopsis: Moderate: qemu-kvm security and bug fix update
Advisory ID: SLSA-2013:0896-1
Issue Date: 2013-06-03
CVE Numbers: CVE-2013-2007

It was found that QEMU Guest Agent (the “qemu-ga” service) created certain
files with world-writable permissions when run in daemon mode (the default
mode). An unprivileged guest user could use this flaw to consume all free
space on the partition containing the qemu-ga log file, or modify the
contents of the log. When a UNIX domain socket transport was explicitly
configured to be used (not the default), an unprivileged guest user could
potentially use this flaw to escalate their privileges in the guest. This
update requires manual action. Refer below for details. (CVE-2013-2007)

This update does not change the permissions of the existing log file or
the UNIX domain socket. For these to be changed, stop the qemu-ga service,
and then manually remove all “group” and “other” permissions on the
affected files, or remove the files.

Note that after installing this update, files created by the guest-file-
open QEMU Monitor Protocol (QMP) command will still continue to be created
with world-writable permissions for backwards compatibility.

This update also fixes the following bugs:

* Previously, due to integer overflow in code calculations, the qemu-kvm
utility was reporting incorrect memory size on QMP events when using the
virtio balloon driver with more than 4 GB of memory. This update fixes the
overflow in the code and qemu-kvm works as expected in the described

* When the set_link flag is set to “off” to change the status of a network
card, the status is changed to “down” on the respective guest. Previously,
with certain network cards, when such a guest was restarted, the status of
the network card was unexpectedly reset to “up”, even though the network
was unavailable. A patch has been provided to address this bug and the
link status change is now preserved across restarts for all network cards.

After installing this update, shut down all running virtual machines. Once
all virtual machines have shut down, start them again for this update to
take effect.


– Scientific Linux Development Team