Initialize data on the stack so that Park doesn't interpret random arguments.

passdata was only being set in pbx_substitue_variables when arguments were
passed.

(closes issue #16406)
(closes issue #16586)
Reported by: DLNoah
Patches: 
      bug16586v2.patch uploaded by jpeeler (license 325)
Tested by: DLNoah



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@241366 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/pbx.c

@@ -3970,8 +3970,10 @@ static void pbx_substitute_variables(char *passdata, int datalen, struct ast_cha
 	const char *tmp;
 
 	/* Nothing more to do */
-	if (!e->data)
+	if (!e->data) {
+		*passdata = '\0';
 		return;
+	}
 
 	/* No variables or expressions in e->data, so why scan it? */
 	if ((!(tmp = strchr(e->data, '$'))) || (!strstr(tmp, "${") && !strstr(tmp, "$["))) {