Mandriva Linux Security Advisory 2009-016 - Ian Jackson found a security issue in the QEMU block device drivers backend that could allow a guest operating system to issue a block device request and read or write arbitrary memory locations, which could then lead to privilege escalation. It was found that Xen allowed unprivileged DomU domains to overwrite xenstore values which should only be changeable by the privileged Dom0 domain. An attacker able to control a DomU domain could possibly use this flaw to kill arbitrary processes in Dom0 or trick a Dom0 user into accessing the text console of a different domain running on the same host. This update makes certain parts of xenstore tree read-only to unprivileged DomU domains. A vulnerability in the qemu-dm.debug script was found in how it created a temporary file in /tmp. A local attacker in Dom0 could potentially use this flaw to overwrite arbitrary files via a symlink attack. Since this script is not used in production, it has been removed from this update package. The updated packages have been patched to prevent these issues.
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