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([2405:201:31:d01f:1c4d:265b:8163:813b]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c6e1967c6fasm5631830a12.1.2026.02.12.03.55.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Feb 2026 03:55:53 -0800 (PST) From: Soham Kute To: axboe@kernel.dk Cc: io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+ab12f0c08dd7ab8d057c@syzkaller.appspotmail.com, Soham Kute Subject: [PATCH] io_uring: fix list corruption race in io_pollfree_wake() Date: Thu, 12 Feb 2026 17:24:58 +0530 Message-Id: <20260212115458.9149-1-officialsohamkute@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit io_pollfree_wake() removes the poll wait entry without holding the waitqueue head lock. Other removal paths take the head lock, so this can race and lead to list corruption detected by list_debug. Acquire the waitqueue lock before calling io_poll_remove_waitq(), matching the locking used in io_poll_remove_entry(). Reported-by: syzbot+ab12f0c08dd7ab8d057c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ab12f0c08dd7ab8d057c Signed-off-by: Soham Kute --- io_uring/poll.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/io_uring/poll.c b/io_uring/poll.c index aac4b3b88..006154355 100644 --- a/io_uring/poll.c +++ b/io_uring/poll.c @@ -383,10 +383,17 @@ static void io_poll_cancel_req(struct io_kiocb *req) static __cold int io_pollfree_wake(struct io_kiocb *req, struct io_poll *poll) { + struct wait_queue_head *head; io_poll_mark_cancelled(req); /* we have to kick tw in case it's not already */ io_poll_execute(req, 0); - io_poll_remove_waitq(poll); + /* Pairs with smp_store_release() in io_poll_remove_waitq() */ + head = smp_load_acquire(&poll->head); + if (head) { + spin_lock_irq(&head->lock); + io_poll_remove_waitq(poll); + spin_unlock_irq(&head->lock); + } return 1; } -- 2.34.1