On Thu, 6 Dec 2018 at 12:55, Linus Walleij linus.walleij@linaro.org wrote:

On Thu, Dec 6, 2018 at 10:45 AM Krzysztof Kozlowski krzk@kernel.org wrote:

...

If CONFIG_GPOILIB is not set, the stub of gpio_to_desc() should return the same type of error as regular version: NULL. All the callers compare the return value of gpio_to_desc() against NULL, so returned ERR_PTR would be treated as non-error case leading to dereferencing of error value.

Fixes: 79a9becda894 ("gpiolib: export descriptor-based GPIO interface") Cc: stable@vger.kernel.org Signed-off-by: Krzysztof Kozlowski krzk@kernel.org

---

include/linux/gpio/consumer.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index ed070512b40e..3b01fbcafc94 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -505,7 +505,7 @@ static inline int gpiod_set_consumer_name(struct gpio_desc *desc,

static inline struct gpio_desc *gpio_to_desc(unsigned gpio) {

•   return ERR_PTR(-EINVAL);
  

•   return NULL;
  

I suppose this is consistent with comitt: 22c403676dbbb7c6f186099527af7f065498ef45 "gpio: return NULL from gpiod_get_optional when GPIOLIB is disabled"

So in that way it should be fine.

I'm just wondering where you see this problem, because IMO a driver that is using GPIO should either depends on GPIOLIB or select GPIOLIB it is extremely uncommon for a GPIO line to actually be optional at compile time (as opposed to optional at runtime) so I would very much like to look closer at this.

No, I did not hit this error. Maybe I should mention this explicitly that this case is rather theoretical (feel free to change the commit msg respectively). What is however important, it misleads developers which test for ERR_PTR, like before this fix: 2d88a331e48095cf60ad9bdf3177bd401bf99727 ("leds: leds-gpio: Fix return value check in create_gpio_led()")

Best regards, Krzysztof