linux-kernel - Re: [PATCH V2] net/sched: Prevent notify to parent who unsupport class ops

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Message-ID: <CAM0EoMneGBL0OkRC_if5VEax-XXXnFAwtpij1J3kOq9NbEPmrA@mail.gmail.com>
Date: Sat, 5 Jul 2025 09:59:19 -0400
From: Jamal Hadi Salim <jhs@...atatu.com>
To: Cong Wang <xiyou.wangcong@...il.com>
Cc: Lizhi Xu <lizhi.xu@...driver.com>, davem@...emloft.net, edumazet@...gle.com, 
	horms@...nel.org, jiri@...nulli.us, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH V2] net/sched: Prevent notify to parent who unsupport
 class ops

On Sat, Jul 5, 2025 at 1:07 AM Cong Wang <xiyou.wangcong@...il.com> wrote:
>
> Hi Lizhi,
>
> On Sat, Jul 05, 2025 at 09:18:22AM +0800, Lizhi Xu wrote:
> > If the parent qdisc does not support class operations then exit notify.
> >
> > In addition, the validity of the cl value is judged before executing the
> > notify. Similarly, the notify is exited when the address represented by
> > its value is invalid.
> >
> > Reported-by: syzbot+1261670bbdefc5485a06@...kaller.appspotmail.com
> > Closes: https://syzkaller.appspot.com/bug?extid=1261670bbdefc5485a06
>
> Maybe I didn't make it clear, I think Victor's patch also fixes this
> bug.
>
> https://lore.kernel.org/netdev/20250704163422.160424-1-victor@mojatatu.com/
>
> Can you check if you still see the crash with his fix?
>

syzbot+1261670bbdefc5485a06@...kaller.appspotmail.com (in this report)
is part of what Victor's patch fixes (as listed in that patch).

cheers,
jamal

> The reason why I am asking is because his fix addresses a problem
> earlier on the code path, which possibly makes your fix unnecessary.
> Hence, his fix is closer to the root cause.
>
> Please test and confirm.
>

V
> Thanks!