Xen is an open source virtualization framework. Virtualization allows users to run guest operating systems in virtual machines on top of a host operating system.
The pyGrub boot loader did not honor the "password" option in the grub.conf file for para-virtualized guests. Users with access to a guest's console could use this flaw to bypass intended access restrictions and boot the guest with arbitrary kernel boot options, allowing them to get root privileges in the guest's operating system. With this update, pyGrub correctly honors the "password" option in grub.conf for para-virtualized guests. (CVE-2009-3525)
This update also fixes the following bugs:
rebooting para-virtualized guests sometimes caused those guests to crash due to a race condition in the xend node control daemon. This update fixes this race condition so that rebooting guests no longer potentially causes them to crash and fail to reboot. (BZ#525141)
due to a race condition in the xend daemon, a guest could disappear from the list of running guests following a reboot, even though the guest rebooted successfully and was running. This update fixes this race condition so that guests always reappear in the guest list following a reboot. (BZ#525143)
attempting to use PCI pass-through to para-virtualized guests on certain kernels failed with a "Function not implemented" error message. As a result, users requiring PCI pass-through on para-virtualized guests were not able to update the xen packages without also updating the kernel and thus requiring a reboot. These updated packages enable PCI pass-through for para-virtualized guests so that users do not need to upgrade the kernel in order to take advantage of PCI pass-through functionality. (BZ#525149)
All Xen users should upgrade to these updated packages, which contain backported patches to correct these issues. After installing the updated packages, the xend service must be restarted for this update to take effect.