io_uring: fix double poll mask init

__io_queue_proc() is used by both, poll reqs and apoll. Don't use
req->poll.events to copy poll mask because for apoll it aliases with
private data of the request.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -5008,6 +5008,8 @@ static void __io_queue_proc(struct io_poll_iocb *poll, struct io_poll_table *pt,
 	 * for write). Setup a separate io_poll_iocb if this happens.
 	 */
 	if (unlikely(poll->head)) {
+		struct io_poll_iocb *poll_one = poll;
+
 		/* already have a 2nd entry, fail a third attempt */
 		if (*poll_ptr) {
 			pt->error = -EINVAL;
@@ -5018,7 +5020,7 @@ static void __io_queue_proc(struct io_poll_iocb *poll, struct io_poll_table *pt,
 			pt->error = -ENOMEM;
 			return;
 		}
-		io_init_poll_iocb(poll, req->poll.events, io_poll_double_wake);
+		io_init_poll_iocb(poll, poll_one->events, io_poll_double_wake);
 		refcount_inc(&req->refs);
 		poll->wait.private = req;
 		*poll_ptr = poll;