diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index a8f575bf9b7c..15f8bd0364c2 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -112,6 +112,13 @@ struct l2tp_net {
 	spinlock_t l2tp_session_hlist_lock;
 };
 
+#if IS_ENABLED(CONFIG_IPV6)
+static bool l2tp_sk_is_v6(struct sock *sk)
+{
+	return sk->sk_family == PF_INET6 &&
+	       !ipv6_addr_v4mapped(&sk->sk_v6_daddr);
+}
+#endif
 
 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk)
 {
@@ -1136,7 +1143,7 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
 	skb->ignore_df = 1;
 	skb_dst_drop(skb);
 #if IS_ENABLED(CONFIG_IPV6)
-	if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped)
+	if (l2tp_sk_is_v6(tunnel->sock))
 		error = inet6_csk_xmit(tunnel->sock, skb, NULL);
 	else
 #endif
@@ -1199,6 +1206,15 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
 		goto out_unlock;
 	}
 
+	/* The user-space may change the connection status for the user-space
+	 * provided socket at run time: we must check it under the socket lock
+	 */
+	if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) {
+		kfree_skb(skb);
+		ret = NET_XMIT_DROP;
+		goto out_unlock;
+	}
+
 	inet = inet_sk(sk);
 	fl = &inet->cork.fl;
 	switch (tunnel->encap) {
@@ -1214,7 +1230,7 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
 
 		/* Calculate UDP checksum if configured to do so */
 #if IS_ENABLED(CONFIG_IPV6)
-		if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
+		if (l2tp_sk_is_v6(sk))
 			udp6_set_csum(udp_get_no_check6_tx(sk),
 				      skb, &inet6_sk(sk)->saddr,
 				      &sk->sk_v6_daddr, udp_len);
@@ -1620,24 +1636,6 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
 	if (cfg != NULL)
 		tunnel->debug = cfg->debug;
 
-#if IS_ENABLED(CONFIG_IPV6)
-	if (sk->sk_family == PF_INET6) {
-		struct ipv6_pinfo *np = inet6_sk(sk);
-
-		if (ipv6_addr_v4mapped(&np->saddr) &&
-		    ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
-			struct inet_sock *inet = inet_sk(sk);
-
-			tunnel->v4mapped = true;
-			inet->inet_saddr = np->saddr.s6_addr32[3];
-			inet->inet_rcv_saddr = sk->sk_v6_rcv_saddr.s6_addr32[3];
-			inet->inet_daddr = sk->sk_v6_daddr.s6_addr32[3];
-		} else {
-			tunnel->v4mapped = false;
-		}
-	}
-#endif
-
 	/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
 	tunnel->encap = encap;
 	if (encap == L2TP_ENCAPTYPE_UDP) {
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 2b9b6fb67ae9..57c1810f1a32 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -191,9 +191,6 @@ struct l2tp_tunnel {
 	struct sock		*sock;		/* Parent socket */
 	int			fd;		/* Parent fd, if tunnel socket
 						 * was created by userspace */
-#if IS_ENABLED(CONFIG_IPV6)
-	bool			v4mapped;
-#endif
 
 	struct work_struct	del_work;