Re: [PATCH 5.15 061/123] gpiolib: check the ngpios property in core gpiolib code

Bartosz Golaszewski
2022-12-12T14:30:50Z

On Mon, Dec 12, 2022 at 2:31 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> From: Bartosz Golaszewski <brgl@bgdev.pl>
>
> [ Upstream commit 9dbd1ab20509e85cd3fac9479a00c59e83c08196 ]
>
> Several drivers read the 'ngpios' device property on their own, but
> since it's defined as a standard GPIO property in the device tree bindings
> anyway, it's a good candidate for generalization. If the driver didn't
> set its gc->ngpio, try to read the 'ngpios' property from the GPIO
> device's firmware node before bailing out.
>
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Stable-dep-of: ec851b23084b ("gpiolib: fix memory leak in gpiochip_setup_dev()")
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/gpio/gpiolib.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index a87c4cd94f7a..b7b5fe151e1a 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -599,6 +599,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
> int base = gc->base;
> unsigned int i;
> int ret = 0;
> + u32 ngpios;
>
> /*
> * First: allocate and populate the internal stat container, and
> @@ -646,6 +647,26 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
> goto err_free_dev_name;
> }
>
> + /*
> + * Try the device properties if the driver didn't supply the number
> + * of GPIO lines.
> + */
> + if (gc->ngpio == 0) {
> + ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);
> + if (ret == -ENODATA)
> + /*
> + * -ENODATA means that there is no property found and
> + * we want to issue the error message to the user.
> + * Besides that, we want to return different error code
> + * to state that supplied value is not valid.
> + */
> + ngpios = 0;
> + else if (ret)
> + goto err_free_descs;
> +
> + gc->ngpio = ngpios;
> + }
> +
> if (gc->ngpio == 0) {
> chip_err(gc, "tried to insert a GPIO chip with zero lines\n");
> ret = -EINVAL;
> --
> 2.35.1
>
>
>

This isn't a fix, please drop it from stable.

Bartosz