Red Hat: RHSA-2012:0370-01 Critical: Xen Heap Overflow Threat

The xen packages contain administration tools and the xend service for managing the kernel-xen kernel for virtualization on Red Hat Enterprise Linux.
A heap overflow flaw was found in the way QEMU emulated the e1000 network interface card. A privileged guest user in a virtual machine whose network interface is configured to use the e1000 emulated driver could use this flaw to crash QEMU or, possibly, escalate their privileges on the host. (CVE-2012-0029)
Red Hat would like to thank Nicolae Mogoreanu for reporting this issue.
This update also fixes the following bugs:
* Adding support for jumbo frames introduced incorrect network device expansion when a bridge is created. The expansion worked correctly with the default configuration, but could have caused network setup failures when a user-defined network script was used. This update changes the expansion so network setup will not fail, even when a user-defined network script is used. (BZ#797191)
* A bug was found in xenconsoled, the Xen hypervisor console daemon. If timestamp logging for this daemon was enabled (using both the XENCONSOLED_TIMESTAMP_HYPERVISOR_LOG and XENCONSOLED_TIMESTAMP_GUEST_LOG options in "/etc/sysconfig/xend"), xenconsoled could crash if the guest emitted a lot of information to its serial console in a short period of time. Eventually, the guest would freeze after the console buffer was filled due to the crashed xenconsoled. Timestamp logging is disabled by default. (BZ#797836)
All xen users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.