Re: [PATCH] gpio: cdev: check if padding of uAPI v2 line config attributes is zeroed

[Kent Gibson]

On Tue, May 19, 2026 at 03:14:53PM +0200, Bartosz Golaszewski wrote:
> We check the padding of other uAPI v2 structures but not that of line
> config attributes. Add the missing check.
> 
> Fixes: 3c0d9c635ae2 ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL")
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpio/gpiolib-cdev.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index f36b7c06996d70b2286edbd181899e4c572b9086..f6f49376a36288cdf44493334e766d6340294ed7 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -1184,6 +1184,7 @@ static int gpio_v2_line_flags_validate(u64 flags)
>  static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
>  					unsigned int num_lines)
>  {
> +	struct gpio_v2_line_config_attribute *attr;
>  	unsigned int i;
>  	u64 flags;
>  	int ret;
> @@ -1194,6 +1195,13 @@ static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
>  	if (!mem_is_zero(lc->padding, sizeof(lc->padding)))
>  		return -EINVAL;
>  
> +	for (i = 0; i < GPIO_V2_LINE_NUM_ATTRS_MAX; i++) {
> +		attr = &lc->attrs[i];
> +
> +		if (!mem_is_zero(&attr->attr.padding, sizeof(attr->attr.padding)))
> +			return -EINVAL;
> +	}
> +

To be really pedantic, how about checking that all the unused attrs are zeroed?
With the loop here reduced to checking the padding of the used attrs.

Also, the attr padding is a u32, so is mem_is_zero() is overkill?

Cheers,
Kent.

>  	for (i = 0; i < num_lines; i++) {
>  		flags = gpio_v2_line_config_flags(lc, i);
>  		ret = gpio_v2_line_flags_validate(flags);
> 
> ---
> base-commit: 6a50ba100ace43f43c87384367eb2d2605fcc16c
> change-id: 20260519-gpio-cdev-attr-padding-check-7e52c98a3de7
> 
> Best regards,
> -- 
> Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
>