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From:   Eric Dumazet <edumazet@google.com>
Date:   Fri, 15 Sep 2023 14:56:14 +0200
Message-ID: <CANn89i+On15D1y92SusrAbMZB9qrNCXZE-PwjzDaF3zpQb7d2g@mail.gmail.com>
Subject: Re: [PATCH] net: sched: qfq: dont intepret cls results when asked to drop
To:     Ma Ke <make_ruc2021@163.com>
Cc:     xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net,
        kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Fri, Sep 15, 2023 at 1:08=E2=80=AFPM Ma Ke <make_ruc2021@163.com> wrote:
>
> If asked to drop a packet via TC_ACT_SHOT it is unsafe to
> assume that res.class contains a valid pointer.
>
> Signed-off-by: Ma Ke <make_ruc2021@163.com>
> ---
>  net/sched/sch_qfq.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
> index 546c10adcacd..20d52dc484b6 100644
> --- a/net/sched/sch_qfq.c
> +++ b/net/sched/sch_qfq.c
> @@ -695,6 +695,8 @@ static struct qfq_class *qfq_classify(struct sk_buff =
*skb, struct Qdisc *sch,
>         *qerr =3D NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
>         fl =3D rcu_dereference_bh(q->filter_list);
>         result =3D tcf_classify(skb, NULL, fl, &res, false);
> +       if (result =3D=3D TC_ACT_SHOT)
> +               return NULL;
>         if (result >=3D 0) {
>  #ifdef CONFIG_NET_CLS_ACT
>                 switch (result) {
> --
> 2.37.2
>

Same comment, it seems already handled at line 706