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From:   Cong Wang <xiyou.wangcong@gmail.com>
Date:   Mon, 30 Aug 2021 22:56:20 -0700
Message-ID: <CAM_iQpWi083uZ5wMYA+coWtME=xQMy3pb-__9jaFqe9piFRSaQ@mail.gmail.com>
Subject: Re: [PATCH V2] fix array-index-out-of-bounds in taprio_change
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Haimin Zhang <tcs.kernel@gmail.com>,
        Vinicius Costa Gomes <vinicius.gomes@intel.com>,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        Jiri Pirko <jiri@resnulli.us>,
        David Miller <davem@davemloft.net>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, tcs_kernel@tencent.com
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On Mon, Aug 30, 2021 at 10:14 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Mon, 30 Aug 2021 11:30:06 +0000 patchwork-bot+netdevbpf@kernel.org
> wrote:
> > Hello:
> >
> > This patch was applied to netdev/net-next.git (refs/heads/master):
> >
> > On Mon, 30 Aug 2021 11:47:01 +0800 you wrote:
> > > From: Haimin Zhang <tcs_kernel@tencent.com>
> > >
> > > syzbot report an array-index-out-of-bounds in taprio_change
> > > index 16 is out of range for type '__u16 [16]'
> > > that's because mqprio->num_tc is lager than TC_MAX_QUEUE,so we check
> > > the return value of netdev_set_num_tc.
> > >
> > > [...]
> >
> > Here is the summary with links:
> >   - [V2] fix array-index-out-of-bounds in taprio_change
> >     https://git.kernel.org/netdev/net-next/c/efe487fce306
> >
> > You are awesome, thank you!
>
> https://lore.kernel.org/netdev/20210830091046.610ceb1b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com/
>
> Oh, well...

I agree it is slightly better to make the check work in
taprio_parse_mqprio_opt(), but this patch is not bad either, we
need to check the return value of netdev_set_num_tc() for
completeness at least.

BTW, this patch should be landed in -net, not -net-next, as it
fixes a real bug reported by syzbot.

Thanks.