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From: Dan Carpenter <[email protected]>
To: Jens Axboe <[email protected]>
Cc: Pavel Begunkov <[email protected]>,
	[email protected], [email protected],
	[email protected]
Subject: [PATCH] io_uring: fix a use after free in io_async_task_func()
Date: Wed, 8 Jul 2020 21:47:11 +0300	[thread overview]
Message-ID: <20200708184711.GA31157@mwanda> (raw)

The "apoll" variable is freed and then used on the next line.  We need
to move the free down a few lines.

Fixes: 0be0b0e33b0b ("io_uring: simplify io_async_task_func()")
Signed-off-by: Dan Carpenter <[email protected]>
---
 fs/io_uring.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 70828e2470e2..f2993070a9e8 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4652,12 +4652,13 @@ static void io_async_task_func(struct callback_head *cb)
 	/* restore ->work in case we need to retry again */
 	if (req->flags & REQ_F_WORK_INITIALIZED)
 		memcpy(&req->work, &apoll->work, sizeof(req->work));
-	kfree(apoll);
 
 	if (!READ_ONCE(apoll->poll.canceled))
 		__io_req_task_submit(req);
 	else
 		__io_req_task_cancel(req, -ECANCELED);
+
+	kfree(apoll);
 }
 
 static int io_async_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
-- 
2.27.0


             reply	other threads:[~2020-07-08 18:49 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-08 18:47 Dan Carpenter [this message]
2020-07-08 19:01 ` [PATCH] io_uring: fix a use after free in io_async_task_func() Pavel Begunkov
2020-07-08 19:14   ` Jens Axboe
2020-07-08 19:15 ` Jens Axboe
2020-07-08 19:28   ` Pavel Begunkov
2020-07-08 19:56     ` Matthew Wilcox
2020-07-09  9:47       ` Pavel Begunkov

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