net/tcp: Separate initialization of twsk

Convert BUG_ON() to WARN_ON_ONCE() and warn as well for unlikely
static key int overflow error-path.
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/tcp_minisocks.c

@@ -240,6 +240,40 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
 }
 EXPORT_SYMBOL(tcp_timewait_state_process);
 
+static void tcp_time_wait_init(struct sock *sk, struct tcp_timewait_sock *tcptw)
+{
+#ifdef CONFIG_TCP_MD5SIG
+	const struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_md5sig_key *key;
+
+	/*
+	 * The timewait bucket does not have the key DB from the
+	 * sock structure. We just make a quick copy of the
+	 * md5 key being used (if indeed we are using one)
+	 * so the timewait ack generating code has the key.
+	 */
+	tcptw->tw_md5_key = NULL;
+	if (!static_branch_unlikely(&tcp_md5_needed.key))
+		return;
+
+	key = tp->af_specific->md5_lookup(sk, sk);
+	if (key) {
+		tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC);
+		if (!tcptw->tw_md5_key)
+			return;
+		if (!tcp_alloc_md5sig_pool())
+			goto out_free;
+		if (!static_key_fast_inc_not_disabled(&tcp_md5_needed.key.key))
+			goto out_free;
+	}
+	return;
+out_free:
+	WARN_ON_ONCE(1);
+	kfree(tcptw->tw_md5_key);
+	tcptw->tw_md5_key = NULL;
+#endif
+}
+
 /*
  * Move a socket to time-wait or dead fin-wait-2 state.
  */
@@ -282,32 +316,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
 		}
 #endif
 
-#ifdef CONFIG_TCP_MD5SIG
-		/*
-		 * The timewait bucket does not have the key DB from the
-		 * sock structure. We just make a quick copy of the
-		 * md5 key being used (if indeed we are using one)
-		 * so the timewait ack generating code has the key.
-		 */
-		do {
-			tcptw->tw_md5_key = NULL;
-			if (static_branch_unlikely(&tcp_md5_needed.key)) {
-				struct tcp_md5sig_key *key;
-
-				key = tp->af_specific->md5_lookup(sk, sk);
-				if (key) {
-					tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC);
-					if (!tcptw->tw_md5_key)
-						break;
-					BUG_ON(!tcp_alloc_md5sig_pool());
-					if (!static_key_fast_inc_not_disabled(&tcp_md5_needed.key.key)) {
-						kfree(tcptw->tw_md5_key);
-						tcptw->tw_md5_key = NULL;
-					}
-				}
-			}
-		} while (0);
-#endif
+		tcp_time_wait_init(sk, tcptw);
 
 		/* Get the TIME_WAIT timeout firing. */
 		if (timeo < rto)