linux-kernel - [PATCH AUTOSEL 5.11 24/44] io_uring: fix ->flags races by linked timeouts

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Message-Id: <20210325112459.1926846-24-sashal@kernel.org>
Date:   Thu, 25 Mar 2021 07:24:39 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Pavel Begunkov <asml.silence@...il.com>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>,
        io-uring@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH AUTOSEL 5.11 24/44] io_uring: fix ->flags races by linked timeouts

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

[ Upstream commit efe814a471e0e58f28f1efaf430c8784a4f36626 ]

It's racy to modify req->flags from a not owning context, e.g. linked
timeout calling req_set_fail_links() for the master request might race
with that request setting/clearing flags while being executed
concurrently. Just remove req_set_fail_links(prev) from
io_link_timeout_fn(), io_async_find_and_cancel() and functions down the
line take care of setting the fail bit.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/io_uring.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 262fd4cfd3ad..b82fe753a6d0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6493,7 +6493,6 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
 	spin_unlock_irqrestore(&ctx->completion_lock, flags);
 
 	if (prev) {
-		req_set_fail_links(prev);
 		io_async_find_and_cancel(ctx, req, prev->user_data, -ETIME);
 		io_put_req_deferred(prev, 1);
 	} else {
-- 
2.30.1