From: Pavel Begunkov <asml.silence@gmail.com>
Date: Fri, 25 Oct 2019 12:31:29 +0300
Subject: io_uring: Fix corrupted user_data
Git-commit: 84d55dc5b9e57b513a702fbc358e1b5489651590
Patch-mainline: 5.4-rc5
References: bnc#1151927 5.3.8

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@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 fs/io_uring.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2150,6 +2150,8 @@ err:
 		return;
 	}
 
+	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