Re: [PATCH] iio: proximity: sx9324: fix out-of-bounds read of scan

[Andy Shevchenko]

On Thu, Oct 22, 2026 at 04:24:11AM +0530, Arnav Kapoor wrote:
> The scan period of the SX9324 is selected by the 5 bit wide
> SX9324_REG_GNRL_CTRL0_SCANPERIOD field, so it has 32 possible values.
> sx9324_scan_period_table[] however only has 16 entries, it was copied
> over from the SX9310 driver where the field is only 4 bits wide.
> 
> sx9324_wait_for_sample() indexes the table with the raw field value, so
> all the codes from 16 to 31 read past the end of the array. The default
> value of the register is SX9324_REG_GNRL_CTRL0_SCANPERIOD_100MS (0x16,
> i.e. 22), so the out-of-bounds read happens with the default
> configuration of the device. It is only avoided when the device has an
> interrupt line, as the wait is only done in the polling case.
> 
> The value read is then used as the duration of an msleep() call, so the
> sensor is polled with a completely random delay.
> 
> Fill the table with the scan periods of all 32 codes, which are the
> periods documented for the corresponding sx9324_samp_freq_table[]
> entries, and add a static assertion to keep both tables in sync.

...

>  static const unsigned int sx9324_scan_period_table[] = {
> -	2,   15,  30,  45,   60,   90,	 120,  200,
> -	400, 600, 800, 1000, 2000, 3000, 4000, 5000,
> +	1, 2, 4, 6, 8, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50,
> +	56, 62, 68, 74, 80, 90, 100, 200, 300, 400, 600, 800, 1000,
> +	2000, 3000, 4000,

NAK to this hunk.
Homework:
read my comments regarding formatting such arrays in linux-iio@ mailing list
for last calendar year or so and summarize the idea.

>  };

...

> +static_assert(ARRAY_SIZE(sx9324_scan_period_table) ==
> +	      ARRAY_SIZE(sx9324_samp_freq_table));

This is fine, but I would dare make it a single line.

-- 
With Best Regards,
Andy Shevchenko