netdev - Re: [PATCH net v3 6/7] net/sched: act_gate: reject empty schedule list

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Message-ID: <c8a8ae22-c5c4-4112-8084-0faa256a1d84@mojatatu.com>
Date: Wed, 21 Jan 2026 16:44:51 -0300
From: Victor Nogueira <victor@...atatu.com>
To: Paul Moses <p@....org>, netdev@...r.kernel.org
Cc: 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>,
 Simon Horman <horms@...nel.org>, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH net v3 6/7] net/sched: act_gate: reject empty schedule
 list

On 21/01/2026 10:20, Paul Moses wrote:
> Reject empty schedules (num_entries == 0) so next_entry is always valid and
> RCU readers/timer logic never walk an empty list. taprio enforces the same
> constraint on schedules (sch_taprio.c, commit 09dbdf28f9f9fa).
> 
> Fixes: a51c328df310 ("net: qos: introduce a gate control flow action")
> Signed-off-by: Paul Moses <p@....org>
> Cc: stable@...r.kernel.org
> ---
>   net/sched/act_gate.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/net/sched/act_gate.c b/net/sched/act_gate.c
> index 48ff378bb051a..e4134b9a4a314 100644
> --- a/net/sched/act_gate.c
> +++ b/net/sched/act_gate.c
> @@ -509,6 +509,12 @@ static int tcf_gate_init(struct net *net, struct nlattr *nla,
>   		cycletime_ext = nla_get_u64(tb[TCA_GATE_CYCLE_TIME_EXT]);
>   	p->tcfg_cycletime_ext = cycletime_ext;
>   
> +	if (p->num_entries == 0) {
> +		NL_SET_ERR_MSG(extack, "The entry list is empty");
> +		err = -EINVAL;
> +		goto release_mem;
> +	}

It would be simpler to check this in parse_gate_list.
That way you could return -EINVAL there directly
in case 0 entries were passed.

cheers,
Victor