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Message-ID: <bca0aca50914367fffccf33b2f2ac880808d6cd9.camel@redhat.com>
Subject: Re: [PATCH net-next v2 1/1] taprio: Add boundary check for
 sched-entry values
From:   Paolo Abeni <pabeni@redhat.com>
To:     Gerhard Engleder <gerhard@engleder-embedded.com>,
        Lai Peter Jun Ann <jun.ann.lai@intel.com>,
        Vinicius Costa Gomes <vinicius.gomes@intel.com>,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Jiri Pirko <jiri@resnulli.us>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Thu, 19 Oct 2023 12:35:30 +0200
In-Reply-To: <27912b49-eb1a-4100-a260-03299e8efdd4@engleder-embedded.com>
References: <1697599707-3546-1-git-send-email-jun.ann.lai@intel.com>
         <27912b49-eb1a-4100-a260-03299e8efdd4@engleder-embedded.com>
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On Wed, 2023-10-18 at 19:56 +0200, Gerhard Engleder wrote:
> On 18.10.23 05:28, Lai Peter Jun Ann wrote:
> > Adds boundary checks for the gatemask provided against the number of
> > traffic class defined for each sched-entry.
> >=20
> > Without this check, the user would not know that the gatemask provided =
is
> > invalid and the driver has already truncated the gatemask provided to
> > match the number of traffic class defined.
> >=20
> > Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@int=
el.com>
> > Signed-off-by: Michael Sit Wei Hong <michael.wei.hong.sit@intel.com>
> > Signed-off-by: Lai Peter Jun Ann <jun.ann.lai@intel.com>
> > ---
> >   net/sched/sch_taprio.c | 8 ++++++++
> >   1 file changed, 8 insertions(+)
> >=20
> > diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
> > index 1cb5e41..44b9e21 100644
> > --- a/net/sched/sch_taprio.c
> > +++ b/net/sched/sch_taprio.c
> > @@ -102,6 +102,7 @@ struct taprio_sched {
> >   	u32 max_sdu[TC_MAX_QUEUE]; /* save info from the user */
> >   	u32 fp[TC_QOPT_MAX_QUEUE]; /* only for dump and offloading */
> >   	u32 txtime_delay;
> > +	u8 num_tc;
> >   };
> >  =20
> >   struct __tc_taprio_qopt_offload {
> > @@ -1063,6 +1064,11 @@ static int fill_sched_entry(struct taprio_sched =
*q, struct nlattr **tb,
> >   		return -EINVAL;
> >   	}
> >  =20
> > +	if (entry->gate_mask >=3D q->num_tc) {
>=20
> As far as I know within gate_mask every bit represents a traffic class.
> So for 3 traffic classes at gate_mask of 0x7 is valid but this check
> fails with 0x7 >=3D 3.

Additionally whatever check we put in place previously just ignored by
the existing code, could break the existing user-space: we can't accept
such change.=20

Cheers,

Paolo