[][[Logan] mwctl command segmentation fault]

[Description]
if run mwctl command without arguments.
it will throw segmentation fault.

root@OpenWrt:~# mwctl
Segmentation fault (core dumped)

[Release-log]


Change-Id: I79f1cb9099168da261eb6903c14ae38857da5a8b
diff --git a/feed/mwctl/src/main.c b/feed/mwctl/src/main.c
index e2421f2..af7b31e 100755
--- a/feed/mwctl/src/main.c
+++ b/feed/mwctl/src/main.c
@@ -80,7 +80,13 @@
 
 	progname = argv[0];
 
-	if_idx = if_nametoindex(argv[1]);
+	if(argv[1])
+		if_idx = if_nametoindex(argv[1]);
+	else {
+		fprintf(stderr, "wrong argument\n");
+		usage();
+	}
+
 	if (!if_idx) {
 		fprintf(stderr, "%s\n", strerror(errno));
 		return 2;