From: Johan Hovold Date: Wed, 12 Apr 2023 12:48:11 +0000 (+0200) Subject: serial: fix TIOCSRS485 locking X-Git-Tag: v6.2.15~613 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9f354556fee41b6ea1bc920af68671e62a1f90b0;p=thirdparty%2Fkernel%2Fstable.git serial: fix TIOCSRS485 locking 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@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 --- diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index ec874f3a567ca..eea526d34fdda 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1552,7 +1552,7 @@ 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); @@ -1595,7 +1595,7 @@ 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;