GPU DDK - UAF read and/or write of arbitrary physical memory due to integer truncation in PMRDevPhysAddrOSMem

Software installed and run as a non-privileged user may conduct improper GPU system calls to cause an integer overflow and map two GPU virtual addresses to the same physical address. One of these virutal mappings can be freed along with the physical page, allowing for a read/write UAF via the second mapping The second virtual mapping references a physical address that has been freed after the first virtual mapping has been freed. This allows the physical memory to be allocated (for example) by another process and read/written to.