VdPersistDisplay - Check if unk1 ptr is NULL

src/xenia/kernel/xboxkrnl_video.cc

@@ -380,11 +380,13 @@ SHIM_CALL VdPersistDisplay_shim(PPCContext* ppc_state, KernelState* state) {
 
   // unk1_ptr needs to be populated with a pointer passed to
   // MmFreePhysicalMemory(1, *unk1_ptr).
+  if (unk1_ptr) {
     auto heap = state->memory()->LookupHeapByType(true, 16 * 1024);
     uint32_t unk1_value;
     heap->Alloc(64, 32, kMemoryAllocationReserve | kMemoryAllocationCommit,
                 kMemoryProtectNoAccess, false, &unk1_value);
     SHIM_SET_MEM_32(unk1_ptr, unk1_value);
+  }
 
   // ?
   SHIM_SET_RETURN_64(1);