ipv4: Missing sk_nulls_node_init() in ping_unhash(). If we don't do that, then the poison value is left in the ->pprev backlink. This can cause crashes if we do a disconnect, followed by a connect(). net/ipv4/ping.c @@ -158,6 +158,7 @@ void ping_unhash(struct sock *sk) if (sk_hashed(sk)) { write_lock_bh(&ping_table.lock); hlist_nulls_del(&sk->sk_nulls_node); + sk_nulls_node_init(&sk->sk_nulls_node); sock_put(sk); isk->inet_num = 0; isk->inet_sport = 0;