Based on a note in asterisk-dev by Brian Capouch, I determined I too agressive in not initializing arrays passed to pbx_substitute_variables_xxxx; I reviewed the code (again) and hopefully found every possible spot where substitute_variables is called conditionally, and made sure the char array involved was set to a null string.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89186 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_mixmonitor.c

@@ -225,6 +225,7 @@ static void launch_monitor_thread(struct ast_channel *chan, const char *filename
 
 	len = sizeof(*mixmonitor) + strlen(chan->name) + strlen(filename) + 2;
 
+	postprocess2[0] = 0;
 	/* If a post process system command is given attach it to the structure */
 	if (!ast_strlen_zero(post_process)) {
 		char *p1, *p2;