[PATCH] staging: greybus: uart: fix uninitialized newline.flow_control

[PATCH] staging: greybus: uart: fix uninitialized newline.flow_control

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Currently newline.flow_control is uninitialized, so it can contain
any garbage from the stack.  I believe it should be initialized with
GB_SERIAL_AUTO_RTSCTS_EN enabled if the termios c_cflag is CRTSCTS
enabled.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/staging/greybus/uart.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c
index 248ad66..b542f67 100644
--- a/drivers/staging/greybus/uart.c
+++ b/drivers/staging/greybus/uart.c
@@ -506,6 +506,8 @@ static void gb_tty_set_termios(struct tty_struct *tty,
 	newline.parity = termios->c_cflag & PARENB ?
 				(termios->c_cflag & PARODD ? 1 : 2) +
 				(termios->c_cflag & CMSPAR ? 2 : 0) : 0;
+	newline.flow_control = termios->c_cflag & CRTSCTS ?
+				GB_SERIAL_AUTO_RTSCTS_EN : 0;
 
 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
-- 
2.10.2

Re: [PATCH] staging: greybus: uart: fix uninitialized newline.flow_control

[Johan Hovold]

On Thu, Feb 09, 2017 at 01:01:18PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Currently newline.flow_control is uninitialized, so it can contain
> any garbage from the stack.  I believe it should be initialized with
> GB_SERIAL_AUTO_RTSCTS_EN enabled if the termios c_cflag is CRTSCTS
> enabled.

Good catch. The CRTSCTS flag is actually honoured a bit further down in
the set_termios(), but there's a bug in that it assumes newline to have
been initialised with the current (old) values. It should
unconditionally set the flow_control field rather than manipulate bits
(we currently use one bit of this field).

Care to send a v2 fixing this up as suggested above?

Thanks,
Johan