Free the buffer as MSDN says

svn path=/trunk/; revision=23040

reactos/ntoskrnl/wmi/wmi.c

@@ -65,6 +65,10 @@ IoWMIWriteEvent(IN PVOID WnodeEventItem)
     DPRINT1("IoWMIWriteEvent() called for WnodeEventItem %p, returning success\n",
         WnodeEventItem);
 
+    /* Free the buffer if we are returning success */
+    if (WnodeEventItem != NULL)
+        ExFreePool(WnodeEventItem);
+
     return STATUS_SUCCESS;
 }