diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
index b1a8e4eec3f6..e63aa6b52460 100644
--- a/net/ipv4/fou.c
+++ b/net/ipv4/fou.c
@@ -213,6 +213,9 @@ static int gue_udp_recv(struct sock *sk, struct sk_buff *skb)
 		return gue_control_message(skb, guehdr);
 
 	proto_ctype = guehdr->proto_ctype;
+	if (unlikely(!proto_ctype))
+		goto drop;
+
 	__skb_pull(skb, sizeof(struct udphdr) + hdrlen);
 	skb_reset_transport_header(skb);