diff --git a/include/linux/udp.h b/include/linux/udp.h
index ae58ff3b6b5b8eb04cca4daabd76b7786d836347..a220880019d6b39e409528889dec0dec5a0a85ff 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -131,6 +131,24 @@ static inline void udp_cmsg_recv(struct msghdr *msg, struct sock *sk,
 	}
 }
 
+DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
+#if IS_ENABLED(CONFIG_IPV6)
+DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
+#endif
+
+static inline bool udp_encap_needed(void)
+{
+	if (static_branch_unlikely(&udp_encap_needed_key))
+		return true;
+
+#if IS_ENABLED(CONFIG_IPV6)
+	if (static_branch_unlikely(&udpv6_encap_needed_key))
+		return true;
+#endif
+
+	return false;
+}
+
 static inline bool udp_unexpected_gso(struct sock *sk, struct sk_buff *skb)
 {
 	if (!skb_is_gso(skb))
@@ -142,6 +160,16 @@ static inline bool udp_unexpected_gso(struct sock *sk, struct sk_buff *skb)
 	if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST && !udp_sk(sk)->accept_udp_fraglist)
 		return true;
 
+	/* GSO packets lacking the SKB_GSO_UDP_TUNNEL/_CSUM bits might still
+	 * land in a tunnel as the socket check in udp_gro_receive cannot be
+	 * foolproof.
+	 */
+	if (udp_encap_needed() &&
+	    READ_ONCE(udp_sk(sk)->encap_rcv) &&
+	    !(skb_shinfo(skb)->gso_type &
+	      (SKB_GSO_UDP_TUNNEL | SKB_GSO_UDP_TUNNEL_CSUM)))
+		return true;
+
 	return false;
 }
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ef41810b48e50c362ab8488996fe15aadfd12d69..0ea08b04a2a7d52b5802a2a9d8b78282a357c6a8 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -602,6 +602,13 @@ static inline bool __udp_is_mcast_sock(struct net *net, struct sock *sk,
 }
 
 DEFINE_STATIC_KEY_FALSE(udp_encap_needed_key);
+EXPORT_SYMBOL(udp_encap_needed_key);
+
+#if IS_ENABLED(CONFIG_IPV6)
+DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
+EXPORT_SYMBOL(udpv6_encap_needed_key);
+#endif
+
 void udp_encap_enable(void)
 {
 	static_branch_inc(&udp_encap_needed_key);
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 0cdd356866ec7d0777b3d41cc0c5ed8bba3bb2fd..ed50a5f33302165f3054d0b878904649288b5f93 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -512,8 +512,10 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
 	unsigned int off = skb_gro_offset(skb);
 	int flush = 1;
 
-	/* we can do L4 aggregation only if the packet can't land in a tunnel
-	 * otherwise we could corrupt the inner stream
+	/* We can do L4 aggregation only if the packet can't land in a tunnel
+	 * otherwise we could corrupt the inner stream. Detecting such packets
+	 * cannot be foolproof and the aggregation might still happen in some
+	 * cases. Such packets should be caught in udp_unexpected_gso later.
 	 */
 	NAPI_GRO_CB(skb)->is_flist = 0;
 	if (!sk || !udp_sk(sk)->gro_receive) {
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index e5ced1f2d812983f884475684e8b293e6454357b..35cca1ec5ca737d497e64349fd605d3f26bf3cdc 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -473,7 +473,7 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	goto try_again;
 }
 
-DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
+DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
 void udpv6_encap_enable(void)
 {
 	static_branch_inc(&udpv6_encap_needed_key);