[PATCH AUTOSEL for 4.15 027/124] gpiolib: don't dereference a desc before validation

Sasha Levin
2018-03-19T22:37:44Z

From: Vladimir Zapolskiy <vz@mleia.com>

[ Upstream commit 30322bcf82d74cad0d6e1cf9ba7fa7fa48c7a026 ]

The fix restores a proper validation of an input gpio desc, which
might be needed to deal with optional GPIOs correctly.

Fixes: 02e479808b5d ("gpio: Alter semantics of *raw* operations to actually be raw")
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/gpio/gpiolib.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index f6efcf94f6ad..8abdd0035091 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2459,7 +2459,7 @@ EXPORT_SYMBOL_GPL(gpiod_direction_output_raw);
*/
int gpiod_direction_output(struct gpio_desc *desc, int value)
{
- struct gpio_chip *gc = desc->gdev->chip;
+ struct gpio_chip *gc;
int ret;

VALIDATE_DESC(desc);
@@ -2476,6 +2476,7 @@ int gpiod_direction_output(struct gpio_desc *desc, int value)
return -EIO;
}

+ gc = desc->gdev->chip;
if (test_bit(FLAG_OPEN_DRAIN, &desc->flags)) {
/* First see if we can enable open drain in hardware */
ret = gpio_set_drive_single_ended(gc, gpio_chip_hwgpio(desc),
--
2.14.1