netdev - Re: [PATCH net-next v2 1/1] taprio: Add boundary check for sched-entry values

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Date: Wed, 18 Oct 2023 19:56:45 +0200
From: Gerhard Engleder <gerhard@...leder-embedded.com>
To: Lai Peter Jun Ann <jun.ann.lai@...el.com>,
 Vinicius Costa Gomes <vinicius.gomes@...el.com>,
 Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>,
 Jiri Pirko <jiri@...nulli.us>, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 1/1] taprio: Add boundary check for
 sched-entry values

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.
> 
> 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.
> 
> Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@...el.com>
> Signed-off-by: Michael Sit Wei Hong <michael.wei.hong.sit@...el.com>
> Signed-off-by: Lai Peter Jun Ann <jun.ann.lai@...el.com>
> ---
>   net/sched/sch_taprio.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> 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;
>   };
>   
>   struct __tc_taprio_qopt_offload {
> @@ -1063,6 +1064,11 @@ static int fill_sched_entry(struct taprio_sched *q, struct nlattr **tb,
>   		return -EINVAL;
>   	}
>   
> +	if (entry->gate_mask >= q->num_tc) {

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 >= 3.

> +		NL_SET_ERR_MSG(extack, "Traffic Class defined less than gatemask");
> +		return -EINVAL;
> +	}
> +
>   	entry->interval = interval;
>   
>   	return 0;
> @@ -1913,6 +1919,8 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
>   		for (i = 0; i <= TC_BITMASK; i++)
>   			netdev_set_prio_tc_map(dev, i,
>   					       mqprio->prio_tc_map[i]);
> +
> +		q->num_tc = mqprio->num_tc;
>   	}
>   
>   	err = parse_taprio_schedule(q, tb, new_admin, extack);