don't allow AUEP responses to overflow the stack during a string copy (reported by Mu Security)

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.2@40057 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_mgcp.c

@@ -2478,12 +2478,14 @@ static void handle_response(struct mgcp_endpoint *p, struct mgcp_subchannel *sub
 						if (strncasecmp(v, p->sub->cxident, len) &&
 						    strncasecmp(v, p->sub->next->cxident, len)) {
 							/* connection id not found. delete it */
-							char cxident[80];
-							memcpy(cxident, v, len);
-							cxident[len] = '\0';
+							char cxident[80] = "";
+
+							if (len > (sizeof(cxident) - 1))
+								len = sizeof(cxident) - 1;
+							ast_copy_string(cxident, v, len);
 							if (option_verbose > 2) {
 								ast_verbose(VERBOSE_PREFIX_3 "Non existing connection id %s on %s@%s \n", 
-									cxident, p->name, gw->name);
+									    cxident, p->name, gw->name);
 							}
 							transmit_connection_del_w_params(p, NULL, cxident);
 						}