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Date:   Mon, 29 Jul 2019 09:47:42 -0700 (PDT)
Message-Id: <20190729.094742.1840605528000035808.davem@davemloft.net>
To:     baijiaju1990@gmail.com
Cc:     jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] net: sched: Fix a possible null-pointer dereference
 in dequeue_func()
From:   David Miller <davem@davemloft.net>
In-Reply-To: <20190729082433.28981-1-baijiaju1990@gmail.com>
References: <20190729082433.28981-1-baijiaju1990@gmail.com>
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From: Jia-Ju Bai <baijiaju1990@gmail.com>
Date: Mon, 29 Jul 2019 16:24:33 +0800

> In dequeue_func(), there is an if statement on line 74 to check whether
> skb is NULL:
>     if (skb)
> 
> When skb is NULL, it is used on line 77:
>     prefetch(&skb->end);
> 
> Thus, a possible null-pointer dereference may occur.
> 
> To fix this bug, skb->end is used when skb is not NULL.
> 
> This bug is found by a static analysis tool STCheck written by us.
> 
> Fixes: 76e3cc126bb2 ("codel: Controlled Delay AQM")
> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>

Applied and queued up for -stable.