Excessive checking in compatibility mode hypercall argument translation

ISSUE DESCRIPTION The hypercall argument translation needed for 32-bit guests running on 64-bit hypervisors performs checks on the final register state. These checks cover all registers potentially holding hypercall arguments, not just the ones actually doing so for the hypercall being processed,...

CVE-2012-4539

Xen 4.0 through 4.2, when running 32-bit x86 PV guests on 64-bit hypervisors, allows local guest OS administrators to cause a denial of service infinite loop and hang or crash via invalid arguments to GNTTABOPgetstatusframes, aka "Grant table hypercall infinite loop DoS vulnerability."...