Re: [PATCH] mwifiex: don't call del_timer_sync() on uninitialized timer

From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: gbhat@marvell.com, amitkarwar@gmail.com, andreyknvl@google.com,
	"David S. Miller" <davem@davemloft.net>,
	Dmitry Vyukov <dvyukov@google.com>,
	huxinming820@gmail.com, Kalle Valo <kvalo@codeaurora.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	USB <linux-usb@vger.kernel.org>,
	"open list:TI WILINK WIRELES..." <linux-wireless@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	Nishant Sarmukadam <nishants@marvell.com>,
	syzbot+dc4127f950da51639216@syzkaller.appspotmail.com,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	syzbot <syzbot+373e6719b49912399d21@syzkaller.appspotmail.com>
Subject: Re: [PATCH] mwifiex: don't call del_timer_sync() on uninitialized timer
Date: Tue, 28 Jul 2020 20:29:05 +0300	[thread overview]
Message-ID: <CAHp75Vdta2xGDH=0CwRf8yK30JQimSGj70-pXz7QUFSgjxoatQ@mail.gmail.com> (raw)
In-Reply-To: <1595900652-3842-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp>

On Tue, Jul 28, 2020 at 4:46 AM Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> syzbot is reporting that del_timer_sync() is called from
> mwifiex_usb_cleanup_tx_aggr() from mwifiex_unregister_dev() without
> checking timer_setup() from mwifiex_usb_tx_init() was called [1].
> Since mwifiex_usb_prepare_tx_aggr_skb() is calling del_timer() if
> is_hold_timer_set == true, use the same condition for del_timer_sync().
>
> [1] https://syzkaller.appspot.com/bug?id=fdeef9cf7348be8b8ab5b847f2ed993aba8ea7b6
>

Can you use BugLink: tag for above?

> Reported-by: syzbot <syzbot+373e6719b49912399d21@syzkaller.appspotmail.com>
> Cc: Ganapathi Bhat <gbhat@marvell.com>
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> ---
> A patch from Ganapathi Bhat ( https://patchwork.kernel.org/patch/10990275/ ) is stalling
> at https://lore.kernel.org/linux-usb/MN2PR18MB2637D7C742BC235FE38367F0A09C0@MN2PR18MB2637.namprd18.prod.outlook.com/ .
> syzbot by now got this report for 10000 times. Do we want to go with this simple patch?
>
>  drivers/net/wireless/marvell/mwifiex/usb.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/marvell/mwifiex/usb.c b/drivers/net/wireless/marvell/mwifiex/usb.c
> index 6f3cfde..04a1461 100644
> --- a/drivers/net/wireless/marvell/mwifiex/usb.c
> +++ b/drivers/net/wireless/marvell/mwifiex/usb.c
> @@ -1353,7 +1353,8 @@ static void mwifiex_usb_cleanup_tx_aggr(struct mwifiex_adapter *adapter)
>                                 skb_dequeue(&port->tx_aggr.aggr_list)))
>                                 mwifiex_write_data_complete(adapter, skb_tmp,
>                                                             0, -1);
> -               del_timer_sync(&port->tx_aggr.timer_cnxt.hold_timer);
> +               if (port->tx_aggr.timer_cnxt.is_hold_timer_set)
> +                       del_timer_sync(&port->tx_aggr.timer_cnxt.hold_timer);
>                 port->tx_aggr.timer_cnxt.is_hold_timer_set = false;
>                 port->tx_aggr.timer_cnxt.hold_tmo_msecs = 0;
>         }
> --
> 1.8.3.1
>

-- 
With Best Regards,
Andy Shevchenko