namespace: append a null byte after readlink

readlink() does not append a null byte to buf.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

namespaces.c

@@ -267,7 +267,7 @@ static unsigned int __get_ns_id(int pid, struct ns_desc *nd, struct ns_id **ns)
 		return 0;
 
 	sprintf(ns_path, "ns/%s", nd->str);
-	ret = readlinkat(proc_dir, ns_path, ns_id, sizeof(ns_id));
+	ret = readlinkat(proc_dir, ns_path, ns_id, sizeof(ns_id) - 1);
 	if (ret < 0) {
 		if (errno == ENOENT) {
 			/* The namespace is unsupported */
@@ -277,6 +277,7 @@ static unsigned int __get_ns_id(int pid, struct ns_desc *nd, struct ns_id **ns)
 		pr_perror("Can't readlink ns link");
 		return 0;
 	}
+	ns_id[ret] = '\0';
 
 	kid = parse_ns_link(ns_id, ret, nd);
 	BUG_ON(!kid);