From 9e4f2a8004213339e9d837d891a59cc80e082966 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 12 Apr 2023 14:48:11 +0200 Subject: [PATCH] serial: fix TIOCSRS485 locking MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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@vger.kernel.org # 6.0 Cc: Ilpo Järvinen Reviewed-by: Ilpo Järvinen Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20230412124811.11217-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index afafbb7edb4a..59b62fa2e287 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -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;