CVE-2026-23439 udp_tunnel: fix NULL deref caused by udp_sock_create6 when CONFIG_IPV6=n

In the Linux kernel, the following vulnerability has been resolved: udptunnel: fix NULL deref caused by udpsockcreate6 when CONFIGIPV6=n When CONFIGIPV6 is disabled, the udpsockcreate6 function returns 0 success without actually creating a socket. Callers such as foucreate then proceed to...