linux-kernel - Re: [PATCH] net: sched: Fix a possible null-pointer dereference in dequeue

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Message-ID: <20190729074125.GB2211@nanopsycho>
Date:   Mon, 29 Jul 2019 09:41:25 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     jhs@...atatu.com, xiyou.wangcong@...il.com, davem@...emloft.net,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: sched: Fix a possible null-pointer dereference in
 dequeue_func()

Mon, Jul 29, 2019 at 09:32:00AM CEST, baijiaju1990@...il.com wrote:
>
>
>On 2019/7/29 14:56, Jiri Pirko wrote:
>> Mon, Jul 29, 2019 at 04:21:57AM CEST, baijiaju1990@...il.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@...il.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.


>
>
>Best wishes,
>Jia-Ju Bai