[PATCH 5.15 056/247] serial: rda-uart: Dont allow CS5-6

[Greg Kroah-Hartman]

From: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>

[ Upstream commit 098333a9c7d12bb3ce44c82f08b4d810c44d31b0 ]

Only CS7 and CS8 are supported but CSIZE is not sanitized after
fallthrough from CS5 or CS6 to CS7.

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().

Fixes: c10b13325ced (tty: serial: Add RDA8810PL UART driver)
Cc: Manivannan Sadhasivam <mani@xxxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220519081808.3776-4-ilpo.jarvinen@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/tty/serial/rda-uart.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/rda-uart.c b/drivers/tty/serial/rda-uart.c
index d550d8fa2fab..a8fe1c3ebcd9 100644
--- a/drivers/tty/serial/rda-uart.c
+++ b/drivers/tty/serial/rda-uart.c
@@ -262,6 +262,8 @@ static void rda_uart_set_termios(struct uart_port *port,
 		fallthrough;
 	case CS7:
 		ctrl &= ~RDA_UART_DBITS_8;
+		termios->c_cflag &= ~CSIZE;
+		termios->c_cflag |= CS7;
 		break;
 	default:
 		ctrl |= RDA_UART_DBITS_8;
-- 
2.35.1