From c069d2756c01ed36121fae6a42c14fdf1325c71d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Date: Thu, 19 May 2022 11:18:05 +0300
Subject: [PATCH] serial: sifive: Sanitize CSIZE and c_iflag
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Git-commit: c069d2756c01ed36121fae6a42c14fdf1325c71d
Patch-mainline: v5.19-rc1
References: git-fixes

Only CS8 is supported but CSIZE was not sanitized to CS8.

Set CSIZE correctly so that userspace knows the effective value.
Incorrect CSIZE also results in miscalculation of the frame bits in
tty_get_char_size() or in its predecessor where the roughly the same
code is directly within uart_update_timeout().

Similarly, INPCK, PARMRK, and BRKINT are reported textually unsupported
but were not cleared in termios c_iflag which is the machine-readable
format.

Fixes: 45c054d0815b (tty: serial: add driver for the SiFive UART)
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220519081808.3776-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/tty/serial/sifive.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index 90010cf7ea9d..c0869b080cc3 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -664,12 +664,16 @@ static void sifive_serial_set_termios(struct uart_port *port,
 	int rate;
 	char nstop;
 
-	if ((termios->c_cflag & CSIZE) != CS8)
+	if ((termios->c_cflag & CSIZE) != CS8) {
 		dev_err_once(ssp->port.dev, "only 8-bit words supported\n");
+		termios->c_cflag &= ~CSIZE;
+		termios->c_cflag |= CS8;
+	}
 	if (termios->c_iflag & (INPCK | PARMRK))
 		dev_err_once(ssp->port.dev, "parity checking not supported\n");
 	if (termios->c_iflag & BRKINT)
 		dev_err_once(ssp->port.dev, "BREAK detection not supported\n");
+	termios->c_iflag &= ~(INPCK|PARMRK|BRKINT);
 
 	/* Set number of stop bits */
 	nstop = (termios->c_cflag & CSTOPB) ? 2 : 1;
-- 
2.35.3