Re: [PATCH V2] fix array-index-out-of-bounds in taprio_change

[Cong Wang]

On Mon, Aug 30, 2021 at 10:14 AM Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
>
> On Mon, 30 Aug 2021 11:30:06 +0000 patchwork-bot+netdevbpf@xxxxxxxxxx
> 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@xxxxxxxxxxx>
> > >
> > > 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@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
>
> 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.