[PATCH 4.9 21/83] fuse: set FR_SENT while locked

Greg Kroah-Hartman
2018-11-19T16:53:09Z

From: Miklos Szeredi <mszeredi@redhat.com>

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@redhat.com>
Reported-by: syzbot+ef054c4d3f64cd7f7cec@syzkaller.appspotmai
Fixes: 46c34a348b0a ("fuse: no fc->lock for pqueue parts")
Cc: <stable@vger.kernel.org> # v4.2
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1311,8 +1311,8 @@ 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))