From cd1508c80dab082c42a9f957357f9c834006d2a6 Mon Sep 17 00:00:00 2001 From: Lino Sanfilippo Date: Wed, 3 Jan 2024 07:18:14 +0100 Subject: [PATCH] serial: core: fix sanitizing check for RTS settings MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit 4afeced55baa391490b61ed9164867e2927353ed upstream. Among other things uart_sanitize_serial_rs485() tests the sanity of the RTS settings in a RS485 configuration that has been passed by userspace. If RTS-on-send and RTS-after-send are both set or unset the configuration is adjusted and RTS-after-send is disabled and RTS-on-send enabled. This however makes only sense if both RTS modes are actually supported by the driver. With commit be2e2cb1d281 ("serial: Sanitize rs485_struct") the code does take the driver support into account but only checks if one of both RTS modes are supported. This may lead to the errorneous result of RTS-on-send being set even if only RTS-after-send is supported. Fix this by changing the implemented logic: First clear all unsupported flags in the RS485 configuration, then adjust an invalid RTS setting by taking into account which RTS mode is supported. Cc: Fixes: be2e2cb1d281 ("serial: Sanitize rs485_struct") Reviewed-by: Ilpo Järvinen Signed-off-by: Lino Sanfilippo Link: https://lore.kernel.org/r/20240103061818.564-4-l.sanfilippo@kunbus.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index f912f8b..e56d34d 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1370,19 +1370,27 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4 return; } + rs485->flags &= supported_flags; + /* Pick sane settings if the user hasn't */ - if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) && - !(rs485->flags & SER_RS485_RTS_ON_SEND) == + if (!(rs485->flags & SER_RS485_RTS_ON_SEND) == !(rs485->flags & SER_RS485_RTS_AFTER_SEND)) { - dev_warn_ratelimited(port->dev, - "%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n", - port->name, port->line); - rs485->flags |= SER_RS485_RTS_ON_SEND; - rs485->flags &= ~SER_RS485_RTS_AFTER_SEND; - supported_flags |= SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND; - } + if (supported_flags & SER_RS485_RTS_ON_SEND) { + rs485->flags |= SER_RS485_RTS_ON_SEND; + rs485->flags &= ~SER_RS485_RTS_AFTER_SEND; - rs485->flags &= supported_flags; + dev_warn_ratelimited(port->dev, + "%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n", + port->name, port->line); + } else { + rs485->flags |= SER_RS485_RTS_AFTER_SEND; + rs485->flags &= ~SER_RS485_RTS_ON_SEND; + + dev_warn_ratelimited(port->dev, + "%s (%d): invalid RTS setting, using RTS_AFTER_SEND instead\n", + port->name, port->line); + } + } uart_sanitize_serial_rs485_delays(port, rs485); -- 2.7.4