Re: [PATCH net v2 5/5] net: restrict message_cost and message_burst to non-negative values

[Fernando Fernandez Mancera]

On 10/27/26 11:45 AM, Jiayuan Chen wrote:
> net.core.message_cost and net.core.message_burst feed the interval and
> burst of net_ratelimit_state, but neither rejects negative values:
> message_burst uses plain proc_dointvec, and message_cost uses
> proc_dointvec_jiffies, which happily stores -1 second as -HZ jiffies.
>
> Since commit a940d145cc38 ("ratelimit: Warn if ->interval or ->burst are
> negative"), ___ratelimit() splats on such values, so the next
> net_ratelimit() caller warns, e.g. a martian source log:
>
>    Negative interval (-250) or burst (10): Uninitialized ratelimit_state structure?
>    WARNING: lib/ratelimit.c:43 at ___ratelimit+0x56e/0x960, CPU#1: ping/3218
>    RIP: 0010:___ratelimit+0x578/0x960
>    Call Trace:
>     <IRQ>
>     net_ratelimit+0x1c/0x30
>     ip_handle_martian_source+0x1bb/0x340
>     ip_route_input_slow+0x1057/0x3650
>     ip_route_input_noref+0x104/0x260
>     arp_process+0x109b/0x2510
>     arp_rcv+0x381/0x460
>     __netif_receive_skb_one_core+0x173/0x1c0
>     __netif_receive_skb+0x21/0x150
>     process_backlog+0x37e/0x1200
>     __napi_poll.constprop.0+0xa5/0x5e0
>     net_rx_action+0x4c0/0xf70
>     handle_softirqs+0x204/0x9b0
>     __do_softirq+0x10/0x18
>     do_softirq.part.0+0x49/0xd0
>     </IRQ>
>
> Negative values never meant anything here: 0 already expresses both
> "no limit" (interval) and "suppress everything" (burst).
>
> Reject them at write time. message_burst can simply use
> proc_dointvec_minmax with extra1 = 0. proc_dointvec_jiffies has no
> minmax variant, so add proc_dointvec_jiffies_minmax(), mirroring
> proc_dointvec_ms_jiffies_minmax(), and use it for message_cost with
> extra1 = 0. Note that like the ms variant, extra1/extra2 are compared
> against the converted jiffies value.
>
> Fixes: a940d145cc38 ("ratelimit: Warn if ->interval or ->burst are negative")
> Cc: stable@xxxxxxxxxxxxxxx
> Suggested-by: Joel Granados <joel.granados@xxxxxxxxxx>
> Signed-off-by: Jiayuan Chen <jiayuan.chen@xxxxxxxxx>
Reviewed-by: Fernando Fernandez Mancera <fmancera@xxxxxxx>

Thanks!