[PATCH 4.19 067/205] fuse: set FR_SENT while locked

[Greg Kroah-Hartman]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Miklos Szeredi <mszeredi@xxxxxxxxxx>

commit 4c316f2f3ff315cb48efb7435621e5bfb81df96d upstream.

Otherwise fuse_dev_do_write() could come in and finish off the request, and
the set_bit(FR_SENT, ...) could trigger the WARN_ON(test_bit(FR_SENT, ...))
in request_end().

Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Reported-by: syzbot+ef054c4d3f64cd7f7cec@xxxxxxxxxxxxxxxxxxxx
Fixes: 46c34a348b0a ("fuse: no fc->lock for pqueue parts")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.2
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1319,8 +1319,8 @@ static ssize_t fuse_dev_do_read(struct f
 	}
 	list_move_tail(&req->list, &fpq->processing);
 	__fuse_get_request(req);
-	spin_unlock(&fpq->lock);
 	set_bit(FR_SENT, &req->flags);
+	spin_unlock(&fpq->lock);
 	/* matches barrier in request_wait_answer() */
 	smp_mb__after_atomic();
 	if (test_bit(FR_INTERRUPTED, &req->flags))