[PATCH v3 2/4] serial: mctrl_gpio: Add a NULL check to mctrl_gpio_to_gpiod()

[Schrempf Frieder]

From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>

As it is allowed to use the mctrl_gpio_* functions before
initialization (as the 8250 driver does according to 434be0ae7aa7),
it seems appropriate to have a NULL check in all of the functions.
Otherwise the mctrl_gpio_to_gpiod() function is prone to be used
in a context that can lead to a NULL pointer dereference.

Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
---
Changes in v3
=============
* Move the changes in mctrl_gpio_to_gpiod() to a separate patch
---
 drivers/tty/serial/serial_mctrl_gpio.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
index 2b400189be91..54c43e02e375 100644
--- a/drivers/tty/serial/serial_mctrl_gpio.c
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -61,6 +61,9 @@ EXPORT_SYMBOL_GPL(mctrl_gpio_set);
 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
 				      enum mctrl_gpio_idx gidx)
 {
+	if (gpios == NULL)
+		return NULL;
+
 	return gpios->gpio[gidx];
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
-- 
2.17.1