PHYSDEVOP_map_pirq in Xen 4.1 and 4.2 and Citrix XenServer 6.0.2 and earlier allows local HVM guest OS kernels to cause a denial of service (host crash) and possibly read hypervisor or guest memory via vectors related to a missing range check of map->index.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.