linux-kernel - [PATCH 3/6] io_uring: don't re-read sqe->off in timeout

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Date:   Tue, 26 May 2020 20:34:04 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/6] io_uring: don't re-read sqe->off in timeout_prep()

SQEs are user writable, don't read sqe->off twice in io_timeout_prep()

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 fs/io_uring.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e30fc17dd268..067ebdeb1ba4 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4803,18 +4803,19 @@ static int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 {
 	struct io_timeout_data *data;
 	unsigned flags;
+	u32 off = READ_ONCE(sqe->off);
 
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
 	if (sqe->ioprio || sqe->buf_index || sqe->len != 1)
 		return -EINVAL;
-	if (sqe->off && is_timeout_link)
+	if (off && is_timeout_link)
 		return -EINVAL;
 	flags = READ_ONCE(sqe->timeout_flags);
 	if (flags & ~IORING_TIMEOUT_ABS)
 		return -EINVAL;
 
-	req->timeout.count = READ_ONCE(sqe->off);
+	req->timeout.count = off;
 
 	if (!req->io && io_alloc_async_ctx(req))
 		return -ENOMEM;
-- 
2.24.0