Fix Potential Double Free

Implementing mem::ManuallyDrop instead of mem::forget

notify/src/windows.rs

@@ -301,10 +301,13 @@ fn start_read(rd: &ReadData, event_handler: Arc<Mutex<dyn EventHandler>>, handle
 
         if ret == 0 {
             // error reading. retransmute request memory to allow drop.
-            // allow overlapped to drop by dropping ManuallyDrop
+            // allow overlapped to drop by omitting forget()
             let request: Box<ReadDirectoryRequest> = mem::transmute(request_p);
-            std::mem::ManuallyDrop::drop(&mut overlapped);
+
             ReleaseSemaphore(request.data.complete_sem, 1, ptr::null_mut());
+        } else {
+            // read ok. forget overlapped to let the completion routine handle memory
+            std::mem::ManuallyDrop::drop(&mut overlapped);
         }
     }
 }