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

[Victor Nogueira]

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@xxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
>   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