netdev - Re: [PATCH net] udp: drop secpath before storing an skb in a receive queue

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Message-ID: <22bfd253-7d0b-4323-8314-5f4f49cc3dd0@redhat.com>
Date: Tue, 14 Oct 2025 10:55:04 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: Sabrina Dubroca <sd@...asysnail.net>,
 "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Simon Horman <horms@...nel.org>, Willem de Bruijn <willemb@...gle.com>,
 netdev@...r.kernel.org, eric.dumazet@...il.com,
 Michal Kubecek <mkubecek@...e.cz>
Subject: Re: [PATCH net] udp: drop secpath before storing an skb in a receive
 queue

On 10/14/25 10:27 AM, Eric Dumazet wrote:
> On Tue, Oct 14, 2025 at 1:06 AM Eric Dumazet <edumazet@...gle.com> wrote:
>> Perhaps not use skb_release_head_state() ?
>>
>> We know there is no dst, and no destructor.
>>
> 
> An no conntrack either from UDP
> 
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 95241093b7f0..932c21838b9b 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1851,8 +1851,13 @@ void skb_consume_udp(struct sock *sk, struct
> sk_buff *skb, int len)
>                 sk_peek_offset_bwd(sk, len);
> 
>         if (!skb_shared(skb)) {
> -               if (unlikely(udp_skb_has_head_state(skb)))
> -                       skb_release_head_state(skb);
> +               if (unlikely(udp_skb_has_head_state(skb))) {
> +                       /* Make sure that skb_release_head_state()
> will have nothing to do. */
> +                       DEBUG_NET_WARN_ON_ONCE(skb_dst(skb));
> +                       DEBUG_NET_WARN_ON_ONCE(skb->destructor);
> +                       DEBUG_NET_WARN_ON_ONCE(skb_nfct(skb));
> +                       skb_ext_reset(skb);
> +               }
>                 skb_attempt_defer_free(skb);
>                 return;
>         }

LGTM, thanks!

/P