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Date:   Tue, 27 Sep 2022 17:26:18 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Duoming Zhou <duoming@zju.edu.cn>
Cc:     linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        isdn@linux-pingi.de
Subject: Re: [PATCH V3] mISDN: fix use-after-free bugs in l1oip timer
 handlers
Message-ID: <20220927172618.58f238d6@kernel.org>
In-Reply-To: <20220924021842.71754-1-duoming@zju.edu.cn>
References: <20220924021842.71754-1-duoming@zju.edu.cn>
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On Sat, 24 Sep 2022 10:18:42 +0800 Duoming Zhou wrote:
> +	del_timer_sync(&hc->keep_tl);
> +	del_timer_sync(&hc->timeout_tl);
> +	cancel_work_sync(&hc->workq);
> +	del_timer_sync(&hc->keep_tl);
>  	cancel_work_sync(&hc->workq);

Why not add a bit which will indicate that the device is shutting 
down and check it in places which schedule the timer?
I think that's much easier to reason about and we won't need to do 
this rep cancel procedure.