Debian: DSA-2666-1 Critical: Xen Denial of Service Risks

Multiple vulnerabilities have been discovered in the Xen hypervisor. The
Common Vulnerabilities and Exposures project identifies the following
problems:

CVE-2013-1918 (XSA 45) Several long latency operations are not preemptible

Some page table manipulation operations for PV guests were not made
preemptible, allowing a malicious or buggy PV guest kernel to mount a
denial of service attack affecting the whole system.

CVE-2013-1952 (XSA 49) VT-d interrupt remapping source validation flaw for bridges

Due to missing source validation on interrupt remapping table
entries for MSI interrupts set up by bridge devices, a malicious
domain with access to such a device, can mount a denial of service
attack affecting the whole system.

CVE-2013-1964 (XSA 50) grant table hypercall acquire/release imbalance

When releasing a particular, non-transitive grant after doing a grant
copy operation Xen incorrectly releases an unrelated grant
reference, leading possibly to a crash of...