This is a note to let you know that I've just added the patch titled
serial: core: make sure RS485 cannot be enabled when it is not supported
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-core-make-sure-rs485-cannot-be-enabled-when-it-is-not-supported.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c73986913fa47e71e0b1ad7f039f6444915e8810 Mon Sep 17 00:00:00 2001
From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Date: Wed, 3 Jan 2024 07:18:15 +0100
Subject: serial: core: make sure RS485 cannot be enabled when it is not supported
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
commit c73986913fa47e71e0b1ad7f039f6444915e8810 upstream.
Some uart drivers specify a rs485_config() function and then decide later
to disable RS485 support for some reason (e.g. imx and ar933).
In these cases userspace may be able to activate RS485 via TIOCSRS485
nevertheless, since in uart_set_rs485_config() an existing rs485_config()
function indicates that RS485 is supported.
Make sure that this is not longer possible by checking the uarts
rs485_supported.flags instead and bailing out if SER_RS485_ENABLED is not
set.
Furthermore instead of returning an empty structure return -ENOTTY if the
RS485 configuration is requested via TIOCGRS485 but RS485 is not supported.
This has a small impact on userspace visibility but it is consistent with
the -ENOTTY error for TIOCGRS485.
Fixes: e849145e1fdd ("serial: ar933x: Fill in rs485_supported")
Fixes: 55e18c6b6d42 ("serial: imx: Remove serial_rs485 sanitization")
Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Signed-off-by: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240103061818.564-5-l.sanfilippo@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/serial_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1453,7 +1453,7 @@ static int uart_set_rs485_config(struct
int ret;
unsigned long flags;
- if (!port->rs485_config)
+ if (!(port->rs485_supported.flags & SER_RS485_ENABLED))
return -ENOTTY;
if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
Patches currently in stable-queue which might be from l.sanfilippo@xxxxxxxxxx are
queue-6.6/serial-omap-do-not-override-settings-for-rs485-support.patch
queue-6.6/serial-core-imx-do-not-set-rs485-enabled-if-it-is-not-supported.patch
queue-6.6/serial-8250_exar-set-missing-rs485_supported-flag.patch
queue-6.6/serial-core-fix-sanitizing-check-for-rts-settings.patch
queue-6.6/serial-core-make-sure-rs485-cannot-be-enabled-when-it-is-not-supported.patch
