From: Johan Hovold <johan@xxxxxxxxxx>
commit 9e4f2a8004213339e9d837d891a59cc80e082966 upstream.
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: ae50bb275283 ("serial: take termios_rwsem for ->rs485_config() & pass termios as param")
Cc: stable@xxxxxxxxxxxxxxx # 6.0
Cc: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230412124811.11217-1-johan@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/serial_core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1552,7 +1552,7 @@ uart_ioctl(struct tty_struct *tty, unsig
goto out;
/* rs485_config requires more locking than others */
- if (cmd == TIOCGRS485)
+ if (cmd == TIOCSRS485)
down_write(&tty->termios_rwsem);
mutex_lock(&port->mutex);
@@ -1595,7 +1595,7 @@ uart_ioctl(struct tty_struct *tty, unsig
}
out_up:
mutex_unlock(&port->mutex);
- if (cmd == TIOCGRS485)
+ if (cmd == TIOCSRS485)
up_write(&tty->termios_rwsem);
out:
return ret;
