Re: [PATCH] iio: adc: stm32-adc: fix possible division by zero in processed channel

[Andy Shevchenko]

On Tue, Sep 15, 2026 at 06:10:40PM +0200, Fabrice Gasnier wrote:
> In case the conversion has failed or returned zero, processing *val
> can lead to a division by zero.
> Need to check for errors, or converted value is zero, before processing
> the data.
> In case converted value is zero, e.g. the Vrefint channel, this should
> be considered as invalid in all case.

Something went very wrong with the indentation of the above.

...

> -		if (mask == IIO_CHAN_INFO_PROCESSED)
> -			*val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val;
> +		if (mask == IIO_CHAN_INFO_PROCESSED) {
> +			if (ret >= 0 && *val)
> +				*val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val;
> +			else
> +				ret = ret < 0 ? ret : -EINVAL;
> +		}

Reuse of the *val makes code harder to follow. Add a temporary variable for
this and do something like this (also note other simplifications)

		tmp_choose_good_name = *val;
		...
		if (mask == IIO_CHAN_INFO_PROCESSED) {
			if (ret < 0)
				return ret;
			if (tmp == 0)
				return -EINVAL;

			*val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / tmp;
		}

>  		iio_device_release_direct(indio_dev);
>  		return ret;

-- 
With Best Regards,
Andy Shevchenko