Kernel memory corruption via stale namespace pointer

Use-after-free in Linux kernel devlink allows local users to read or corrupt kernel memory through generic Netlink queries. During devlink_init(), registering the generic Netlink family before per-network operations can leave devlink objects holding a freed struct net pointer if later registration fails. An unprivileged local user can reach that pointer through DEVLINK_CMD get or dump handlers; exploitation requires the rare boot-time failure and can disclose memory, corrupt kernel state, or panic the host.