CVE-2017-10921: xen: grant table operations mishandle reference counts (XSA-224)

Severity: Critical

CVSS Score: 10

The grant-table feature in Xen through 4.8.x does not ensure sufficient type counts for a GNTMAP_device_map and GNTMAP_host_map mapping, which allows guest OS users to cause a denial of service (count mismanagement and memory corruption) or obtain privileged host OS access, aka XSA-224 bug 2.