Commit dc8c8437 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

tty: moxa: fix TIOCSSERIAL permission check 



Changing the port close delay or type are privileged operations so make
sure to return -EPERM if a regular user tries to change them.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210407102334.32361-12-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6e70b73c

drivers/tty/moxa.c

+11 −5
Original line number Diff line number Diff line
@@ -2048,6 +2048,7 @@ static int moxa_set_serial_info(struct tty_struct *tty, 
		struct serial_struct *ss)

{

	struct moxa_port *info = tty->driver_data;

	unsigned int close_delay;



	if (tty->index == MAX_PORTS)

		return -EINVAL;
@@ -2059,19 +2060,24 @@ static int moxa_set_serial_info(struct tty_struct *tty, 
			ss->baud_base != 921600)

		return -EPERM;



	close_delay = msecs_to_jiffies(ss->close_delay * 10);



	mutex_lock(&info->port.mutex);

	if (!capable(CAP_SYS_ADMIN)) {

		if (((ss->flags & ~ASYNC_USR_MASK) !=

		if (close_delay != info->port.close_delay ||

		    ss->type != info->type ||

		    ((ss->flags & ~ASYNC_USR_MASK) !=

		     (info->port.flags & ~ASYNC_USR_MASK))) {

			mutex_unlock(&info->port.mutex);

			return -EPERM;

		}

	}

	info->port.close_delay = msecs_to_jiffies(ss->close_delay * 10);

	} else {

		info->port.close_delay = close_delay;



		MoxaSetFifo(info, ss->type == PORT_16550A);



		info->type = ss->type;

	}

	mutex_unlock(&info->port.mutex);

	return 0;

}