linux-kernel - [PATCH 1/3] io_uring: Fix corrupted user

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Date:   Fri, 25 Oct 2019 12:31:29 +0300
From:   "Pavel Begunkov (Silence)" <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Pavel Begunkov <asml.silence@...il.com>
Subject: [PATCH 1/3] io_uring: Fix corrupted user_data

From: Pavel Begunkov <asml.silence@...il.com>

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@...il.com>
---
 fs/io_uring.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1b46c72f8975..0e141d905a5b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2448,6 +2448,8 @@ static void io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
 		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
-- 
2.23.0