CVE-2026-12234 TOCTOU double-fetch in `zsock_sendmsg`/`recvmsg` userspace verifiers allows kernel-heap out-of-bounds write

The userspace syscall verifiers zvrfyzsocksendmsg and zvrfyzsockrecvmsg in subsys/net/lib/sockets/sockets.c snapshot the caller-supplied struct netmsghdr into a kernel-side copy with kusermodefromcopy, but then re-read the still-live user struct for subsequent decisions. The kernel iovec shadow...