Make sure that *really* no more than sizeof(ifr.ifr_name) chars are strcpy-ed to…

Make sure that *really* no more than sizeof(ifr.ifr_name) chars are strcpy-ed to ifr.ifr_name and that the string is *always* NUL terminated. New code shouldn't use strcpy(), too. CID 719692

Modules/socketmodule.c

@@ -1674,7 +1674,8 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             if (len == 0) {
                 ifr.ifr_ifindex = 0;
             } else if (len < sizeof(ifr.ifr_name)) {
-                strcpy(ifr.ifr_name, PyBytes_AS_STRING(interfaceName));
+                strncpy(ifr.ifr_name, PyBytes_AS_STRING(interfaceName), sizeof(ifr.ifr_name));
+                ifr.ifr_name[(sizeof(ifr.ifr_name))-1] = '\0';
                 if (ioctl(s->sock_fd, SIOCGIFINDEX, &ifr) < 0) {
                     s->errorhandler();
                     Py_DECREF(interfaceName);