Re: [PATCH net] udp: prevent skbs lingering in tunnel socket queues

[Cong Wang]

On Thu, May 19, 2016 at 6:58 AM, Hannes Frederic Sowa
<han...@stressinduktion.org> wrote:
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 2e3ebfe5549ef5..d56c0559b477cb 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1565,7 +1565,7 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff 
> *skb)
>
>                 /* if we're overly short, let UDP handle it */
>                 encap_rcv = ACCESS_ONCE(up->encap_rcv);
> -               if (skb->len > sizeof(struct udphdr) && encap_rcv) {
> +               if (encap_rcv) {


I don't think you can just remove it here, l2tp_udp_recv_core() still
relies on it:

        /* UDP has verifed checksum */

        /* UDP always verifies the packet length. */
        __skb_pull(skb, sizeof(struct udphdr));