[PATCH 5.3 095/197] io_uring: Fix corrupted user_data

From: Greg Kroah-Hartman
Date: Sun Oct 27 2019 - 17:21:24 EST

From: Pavel Begunkov <asml.silence@xxxxxxxxx>

commit 84d55dc5b9e57b513a702fbc358e1b5489651590 upstream.

There is a bug, where failed linked requests are returned not with
specified @user_data, but with garbage from a kernel stack.

The reason is that io_fail_links() uses req->user_data, which is
uninitialised when called from io_queue_sqe() on fail path.

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, 2 insertions(+)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2157,6 +2157,8 @@ err:

+ req->user_data = s->sqe->user_data;
* If we already have a head request, queue this one for async
* submittal once the head completes. If we don't have a head but