Fix some UB in signal handling

can.c

@@ -69,7 +69,6 @@ static void can_exit(struct ios_ops *ios)
 	shutdown(ios->fd, SHUT_RDWR);
 	close(ios->fd);
 	pthread_join(can_thread, NULL);
-	free(ios);
 }
 
 static void *can_thread_fun(void *_data)

commands.c

@@ -147,7 +147,10 @@ static int cmd_break(int argc, char *argv[])
 
 static int cmd_quit(int argc, char *argv[])
 {
+	fflush(NULL);
 	microcom_exit(0);
+	free(ios);
+	exit(0);
 	return 0;
 }
 

microcom.c

@@ -150,12 +150,13 @@ int flag_to_baudrate(speed_t speed)
 
 void microcom_exit(int signal)
 {
-	printf("exiting\n");
+	write(1, "exiting\n", 8);
 
 	ios->exit(ios);
 	tcsetattr(STDIN_FILENO, TCSANOW, &sots);
 
-	exit(0);
+	if (signal)
+		_Exit(0);
 }
 
 /********************************************************************
@@ -202,7 +203,7 @@ int listenonly = 0;
 
 int main(int argc, char *argv[])
 {
-	struct sigaction sact;  /* used to initialize the signal handler */
+	struct sigaction sact = {0};  /* used to initialize the signal handler */
 	int opt, ret;
 	char *hostport = NULL;
 	int telnet = 0, can = 0;
@@ -319,6 +320,7 @@ int main(int argc, char *argv[])
 		/* set the signal handler to restore the old
 		 * termios handler */
 		sact.sa_handler = &microcom_exit;
+		sigemptyset(&sact.sa_mask);
 		sigaction(SIGHUP, &sact, NULL);
 		sigaction(SIGINT, &sact, NULL);
 		sigaction(SIGPIPE, &sact, NULL);

serial.c

@@ -136,7 +136,6 @@ static void serial_exit(struct ios_ops *ios)
 {
 	tcsetattr(ios->fd, TCSANOW, &pots);
 	close(ios->fd);
-	free(ios);
 	serial_unlock();
 }
 

telnet.c

@@ -76,7 +76,6 @@ static int telnet_send_break(struct ios_ops *ios)
 static void telnet_exit(struct ios_ops *ios)
 {
 	close(ios->fd);
-	free(ios);
 }
 
 struct ios_ops *telnet_init(char *hostport)