kernel: ip6_tunnel: clear skb2->cb[] in ip4ip6_err()

In the Linux kernel, the following vulnerability has been resolved: ip6tunnel: clear skb2-cb in ip4ip6err Oskar Kjos reported the following problem. ip4ip6err calls icmpsend on a cloned skb whose cb was written by the IPv6 receive path as struct inet6skbparm. icmpsend passes IPCBskb2 to...