On Thu, Jul 6, 2023 at 1:41 AM Kuniyuki Iwashima kuniyu@amazon.com wrote:
Sorry for late reply.
What we know about sk before inet6?_lookup_reuseport() are
(1) sk was full socket in bpf_sk_assign() (2) sk had SOCK_RCU_FREE in bpf_sk_assign() (3) sk was TCP_LISTEN here if TCP
Are we looking at the same bpf_sk_assign? Confusingly there are two very similarly named functions. The one we care about is:
BPF_CALL_3(bpf_sk_assign, struct sk_buff *, skb, struct sock *, sk, u64, flags) { if (!sk || flags != 0) return -EINVAL; if (!skb_at_tc_ingress(skb)) return -EOPNOTSUPP; if (unlikely(dev_net(skb->dev) != sock_net(sk))) return -ENETUNREACH; if (sk_is_refcounted(sk) && unlikely(!refcount_inc_not_zero(&sk->sk_refcnt))) return -ENOENT;
skb_orphan(skb); skb->sk = sk; skb->destructor = sock_pfree;
return 0; }
From this we can't tell what state the socket is in or whether it is RCU freed or not.
Thanks Lorenz