Re: [PATCH] iio: humidity: hts221: fix division by zero in calibration data parsing

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Tue, Aug 25, 2026 at 05:21:10PM +0800, Yang Zi wrote:
> hts221_parse_temp_caldata() and hts221_parse_rh_caldata() compute the
> sensor slope as ((cal_y1 - cal_y0) * 8000) / (cal_x1 - cal_x0). If the
> device reports cal_x1 == cal_x0 the division causes a divide-by-zero
> error.
> 
> Return -EINVAL when cal_x1 == cal_x0 in both functions before performing
> the division.

Do you have HW to test? Any fault injection perhaps?
The problem with div-by-0 is that it's implementation defined, meaning
that it's how compiler decides. Now, the question is, what will compiler
do in the current code (no patch applied)?

...

>          return err;

>      cal_x1 = le16_to_cpu(val);

>  

I would remove this blank line as it's coupled with the above.

> +    if (cal_x1 == cal_x0)
> +        return -EINVAL;
> +

>      slope = &hw->sensors[HTS221_SENSOR_T].slope;
>      b_gen = &hw->sensors[HTS221_SENSOR_T].b_gen;

Ditto for the rest.


-- 
With Best Regards,
Andy Shevchenko