From deb309ffda4facaedbcbe47dcfe37a5a6d0cc788 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
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
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 <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20230412124811.11217-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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 2bd32c8ece39..728cb72be066 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;
--
GitLab