kernel: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()

A flaw was found in the Linux kernel's IPv6 ICMP error generation. A remote attacker could send a specially crafted IPv4 ICMP error packet with a Common Internet Protocol Security Option CIPSO IP option. This could lead to incorrect handling of packet control block data when generating an IPv6 IC...