From mboxrd@z Thu Jan 1 00:00:00 1970 From: jiangyiwen Subject: Re: [V9fs-developer] [PATCH] /net/9p/trans_fd.c: fix race-condition by flushing workqueue before the kfree() Date: Fri, 20 Jul 2018 16:34:56 +0800 Message-ID: <5B519EB0.8000700@huawei.com> References: <20180719200607.30286-1-tomasbortoli@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Cc: , , , , To: Tomas Bortoli , , , Return-path: In-Reply-To: <20180719200607.30286-1-tomasbortoli@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 2018/7/20 4:06, Tomas Bortoli wrote: > 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 > 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 call flush_scheduled_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..76ae134c05d9 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_scheduled_work(); I suggest we should use flush_work(&p9_poll_work), flush_scheduled_work is not suitable. Thanks. > } > > /** >