* [PATCH] [V9fs-developer] [PATCH] /net/9p/trans_fd.c: fix race-condition by flushing workqueue before the kfree()
@ 2018-07-20 9:27 Tomas Bortoli
2018-07-23 2:39 ` Dominique Martinet
0 siblings, 1 reply; 2+ messages in thread
From: Tomas Bortoli @ 2018-07-20 9:27 UTC (permalink / raw)
To: ericvh, rminnich, lucho
Cc: jiangyiwen, davem, v9fs-developer, netdev, linux-kernel,
syzkaller, Tomas Bortoli
The patch adds the flush in p9_mux_poll_stop() as it the function used by
p9_conn_destroy(), in turn called by p9_fd_close() to stop the async
polling associated with the data regarding the connection.
Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+39749ed7d9ef6dfb23f6@syzkaller.appspotmail.com
---
As shown by Syzbot, it is possible to provoke a race between p9_fd_close()
and p9_poll_workfn() that is called to take care of the async read/write work
to do. To make sure p9_fd_close() frees "trans" when it is not used anymore,
it has to explicitly flush p9_poll_work before the kfree().
net/9p/trans_fd.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index bf459ee0feab..a64b01c56e30 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -185,6 +185,8 @@ static void p9_mux_poll_stop(struct p9_conn *m)
spin_lock_irqsave(&p9_poll_lock, flags);
list_del_init(&m->poll_pending_link);
spin_unlock_irqrestore(&p9_poll_lock, flags);
+
+ flush_work(&p9_poll_work);
}
/**
--
2.11.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] [V9fs-developer] [PATCH] /net/9p/trans_fd.c: fix race-condition by flushing workqueue before the kfree()
2018-07-20 9:27 [PATCH] [V9fs-developer] [PATCH] /net/9p/trans_fd.c: fix race-condition by flushing workqueue before the kfree() Tomas Bortoli
@ 2018-07-23 2:39 ` Dominique Martinet
0 siblings, 0 replies; 2+ messages in thread
From: Dominique Martinet @ 2018-07-23 2:39 UTC (permalink / raw)
To: Tomas Bortoli
Cc: ericvh, rminnich, lucho, jiangyiwen, davem, v9fs-developer,
netdev, linux-kernel, syzkaller
Tomas Bortoli wrote on Fri, Jul 20, 2018:
> The patch adds the flush in p9_mux_poll_stop() as it the function used by
> p9_conn_destroy(), in turn called by p9_fd_close() to stop the async
> polling associated with the data regarding the connection.
>
> Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
> Reported-by: syzbot+39749ed7d9ef6dfb23f6@syzkaller.appspotmail.com
Looks good to me, I'm taking this patch.
If I had to say something, try to aim for slightly shorter subject lines
if possible :)
> ---
> As shown by Syzbot, it is possible to provoke a race between p9_fd_close()
> and p9_poll_workfn() that is called to take care of the async read/write work
> to do. To make sure p9_fd_close() frees "trans" when it is not used anymore,
> it has to explicitly flush p9_poll_work before the kfree().
>
> net/9p/trans_fd.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
> index bf459ee0feab..a64b01c56e30 100644
> --- a/net/9p/trans_fd.c
> +++ b/net/9p/trans_fd.c
> @@ -185,6 +185,8 @@ static void p9_mux_poll_stop(struct p9_conn *m)
> spin_lock_irqsave(&p9_poll_lock, flags);
> list_del_init(&m->poll_pending_link);
> spin_unlock_irqrestore(&p9_poll_lock, flags);
> +
> + flush_work(&p9_poll_work);
> }
>
> /**
--
Dominique Martinet
^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-07-20 9:27 [PATCH] [V9fs-developer] [PATCH] /net/9p/trans_fd.c: fix race-condition by flushing workqueue before the kfree() Tomas Bortoli
2018-07-23 2:39 ` Dominique Martinet
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