[PATCH 5.6 102/161] io_uring: fix flush req->refs underflow

[Greg Kroah-Hartman]

From: Pavel Begunkov <asml.silence@xxxxxxxxx>

commit 4518a3cc273cf82efdd36522fb1f13baad173c70 upstream.

In io_uring_cancel_files(), after refcount_sub_and_test() leaves 0
req->refs, it calls io_put_req(), which would also put a ref. Call
io_free_req() instead.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 2ca10259b418 ("io_uring: prune request from overflow list on flush")
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/io_uring.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6529,7 +6529,7 @@ static void io_uring_cancel_files(struct
 			 * all we had, then we're done with this request.
 			 */
 			if (refcount_sub_and_test(2, &cancel_req->refs)) {
-				io_put_req(cancel_req);
+				io_free_req(cancel_req);
 				finish_wait(&ctx->inflight_wait, &wait);
 				continue;
 			}