netdev - Re: [PATCH 1/4] sched: Avoid dereferencing skb pointer after child enqueue

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Message-ID: <871s5muu25.fsf@toke.dk>
Date:   Wed, 09 Jan 2019 09:14:10 +0100
From:   Toke Høiland-Jørgensen <toke@...e.dk>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Cake List <cake@...ts.bufferbloat.net>,
        Toke Høiland-Jørgensen <toke@...hat.com>
Subject: Re: [PATCH 1/4] sched: Avoid dereferencing skb pointer after child enqueue

Cong Wang <xiyou.wangcong@...il.com> writes:

> On Mon, Jan 7, 2019 at 11:50 AM Toke Høiland-Jørgensen <toke@...e.dk> wrote:
>> @@ -1254,7 +1256,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
>>         if (cl->qdisc->q.qlen != 1) {
>>                 if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) &&
>
>
> Isn't this comparison problematic too? While you are on it...

Well, I was only looking at safety issues, and since it's not
dereferencing the pointer, that's not really an issue here. The check is
just going to always fail if GSO splitting is enabled. Which I'm not
actually sure is an error in this case?

-Toke