In the Linux kernel, the following vulnerability has been resolved:
fou: Don't allow 0 for FOUATTRIPPROTO.
fouudprecv() has the same problem mentioned in the previous patch.
If FOUATTRIPPROTO is set to 0, skb is not freed by fouudprecv() nor "resubmit"-ted in ipprotocoldeliver_rcu().
Let's forbid 0 for FOUATTRIPPROTO.