--- a/net/ipv4/fou.c
+++ b/net/ipv4/fou.c
@@ -1008,6 +1008,9 @@ static int gue_err_proto_handler(int proto, struct sk_buff *skb, u32 info)
 {
        const struct net_protocol *ipprot = rcu_dereference(inet_protos[proto]);
 
+       if (ipprot == IPPROTO_UDP)
+               return -EINVAL;
+
        if (ipprot && ipprot->err_handler) {
                if (!ipprot->err_handler(skb, info))
                        return 0;