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Subject: Re: [PATCH] net: sched: Fix a possible null-pointer dereference in
 dequeue_func()
To:     Jiri Pirko <jiri@resnulli.us>
Cc:     jhs@mojatatu.com, xiyou.wangcong@gmail.com, davem@davemloft.net,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20190729022157.18090-1-baijiaju1990@gmail.com>
 <20190729065653.GA2211@nanopsycho>
 <4752bf67-7a0c-7bc9-3d54-f18361085ba2@gmail.com>
 <20190729074125.GB2211@nanopsycho>
From:   Jia-Ju Bai <baijiaju1990@gmail.com>
Message-ID: <5a8fc4cb-4ee8-b2be-2b14-90e8285fef07@gmail.com>
Date:   Mon, 29 Jul 2019 15:59:10 +0800
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On 2019/7/29 15:41, Jiri Pirko wrote:
> Mon, Jul 29, 2019 at 09:32:00AM CEST, baijiaju1990@gmail.com wrote:
>>
>> On 2019/7/29 14:56, Jiri Pirko wrote:
>>> Mon, Jul 29, 2019 at 04:21:57AM CEST, baijiaju1990@gmail.com wrote:
>>>> 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.
>>>>
>>>> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
>>> Fixes tag, please?
>> Sorry, I do not know what "fixes tag" means...
>> I just find a possible bug and fix it in this patch.
> git log |grep Fixes:
>
> If A fix goes to -net tree, it most probably fixes some bug introduced
> by some commit in the past. So this tag is to put a reference.

Thanks for the explanation.
I will add it and submit a v2 patch.


Best wishes,
Jia-Ju Bai