[PATCH 4.15 025/168] gpiolib: dont dereference a desc before validation

From: Greg Kroah-Hartman
Date: Tue Apr 10 2018 - 18:26:55 EST


4.15-stable review patch. If anyone has any objections, please let me know.

------------------

From: Vladimir Zapolskiy <vz@xxxxxxxxx>


[ 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@xxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpio/gpiolib.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2468,7 +2468,7 @@ EXPORT_SYMBOL_GPL(gpiod_direction_output
*/
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);
@@ -2485,6 +2485,7 @@ int gpiod_direction_output(struct gpio_d
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),