Commit 9e4f2a80 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

serial: fix TIOCSRS485 locking 



The RS485 multipoint addressing support for some reason added a new
ADDRB termios cflag which is (only!) updated from one of the RS485
ioctls.

Make sure to take the termios rw semaphore for the right ioctl (i.e.
set, not get).

Fixes: ae50bb27 ("serial: take termios_rwsem for ->rs485_config() & pass termios as param")
Cc: stable@vger.kernel.org	# 6.0
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20230412124811.11217-1-johan@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c6c01763

drivers/tty/serial/serial_core.c

+2 −2
Original line number Diff line number Diff line
@@ -1549,7 +1549,7 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg) 
		goto out;



	/* rs485_config requires more locking than others */

	if (cmd == TIOCGRS485)

	if (cmd == TIOCSRS485)

		down_write(&tty->termios_rwsem);



	mutex_lock(&port->mutex);
@@ -1592,7 +1592,7 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg) 
	}

out_up:

	mutex_unlock(&port->mutex);

	if (cmd == TIOCGRS485)

	if (cmd == TIOCSRS485)

		up_write(&tty->termios_rwsem);

out:

	return ret;