[PATCH AUTOSEL 4.19 074/100] serial: mctrl_gpio: Check for NULL pointer

[Sasha Levin]

From: Adam Ford <aford173@xxxxxxxxx>

[ Upstream commit 37e3ab00e4734acc15d96b2926aab55c894f4d9c ]

When using mctrl_gpio_to_gpiod, it dereferences gpios into a single
requested GPIO.  This dereferencing can break if gpios is NULL,
so this patch adds a NULL check before dereferencing it.  If
gpios is NULL, this function will also return NULL.

Signed-off-by: Adam Ford <aford173@xxxxxxxxx>
Reviewed-by: Yegor Yefremov <yegorslists@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20191006163314.23191-1-aford173@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 07f318603e740..af0412a784d27 100644
--- a/drivers/tty/serial/serial_mctrl_gpio.c
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -60,6 +60,9 @@ 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);
-- 
2.20.1