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From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
	io-uring@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2] io_uring: Fix ->data corruption on re-enqueue
Date: Mon, 23 Mar 2020 11:19:14 +0300
Message-ID: <dfc0b13b8ccc5f7780fd94c1f7e4db724ac7513d.1584951486.git.asml.silence@gmail.com> (raw)
In-Reply-To: <c8d9cc69995858fd8859b339f77901f93574c528.1584912194.git.asml.silence@gmail.com>

work->data and work->list are shared in union. io_wq_assign_next() sets
->data if a req having a linked_timeout, but then io-wq may want to use
work->list, e.g. to do re-enqueue of a request, so corrupting ->data.

Don't need ->data, remove it and get linked_timeout through @link_list.

Fixes: 60cf46ae6054 ("io-wq: hash dependent work")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io-wq.h    | 5 +----
 fs/io_uring.c | 9 ++++-----
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/fs/io-wq.h b/fs/io-wq.h
index 298b21f4a4d2..d2a5684bf673 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -63,10 +63,7 @@ static inline void wq_node_del(struct io_wq_work_list *list,
 } while (0)
 
 struct io_wq_work {
-	union {
-		struct io_wq_work_node list;
-		void *data;
-	};
+	struct io_wq_work_node list;
 	void (*func)(struct io_wq_work **);
 	struct files_struct *files;
 	struct mm_struct *mm;
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5267e331b4a4..ce8f38aa070a 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1567,9 +1567,10 @@ static void io_free_req(struct io_kiocb *req)
 
 static void io_link_work_cb(struct io_wq_work **workptr)
 {
-	struct io_wq_work *work = *workptr;
-	struct io_kiocb *link = work->data;
+	struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work);
+	struct io_kiocb *link;
 
+	link = list_first_entry(&req->link_list, struct io_kiocb, link_list);
 	io_queue_linked_timeout(link);
 	io_wq_submit_work(workptr);
 }
@@ -1584,10 +1585,8 @@ static void io_wq_assign_next(struct io_wq_work **workptr, struct io_kiocb *nxt)
 
 	*workptr = &nxt->work;
 	link = io_prep_linked_timeout(nxt);
-	if (link) {
+	if (link)
 		nxt->work.func = io_link_work_cb;
-		nxt->work.data = link;
-	}
 }
 
 /*
-- 
2.24.0


  parent reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-22 21:23 [PATCH 1/1] " Pavel Begunkov
2020-03-23  1:28 ` Jens Axboe
2020-03-23  8:19 ` Pavel Begunkov [this message]
2020-03-23 14:25   ` [PATCH v2] " Jens Axboe

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