Re: [PATCH] iio: gts-helper: add __counted_by_ptr to struct iio_gts

[Matti Vaittinen <mazziesaccount@gmail.com>]

On 23/09/2026 07:16, Bill Wendling wrote:
> The compiler attribute __counted_by_ptr can be used by KASAN and UBSAN
> to detect out-of-bounds accesses to pointer fields in structs where a
> corresponding element count field is available.
> 
> In "struct iio_gts", there are multiple pointer fields associated with
> an element count. This patch annotates these pointer fields with
> "__counted_by_ptr" to improve runtime safety:
> 
> - 'hwgain_table': counted by 'num_hwgain'
> - 'itime_table': counted by 'num_itime'
> - 'per_time_avail_scale_tables': counted by 'num_itime'
> - 'avail_all_scales_table': counted by 'num_avail_all_scales'
> - 'avail_time_tables': counted by 'num_avail_time_tables'
> 
> To ensure that the count is set correctly before any pointer is
> accessed or assigned, we update "iio_init_iio_gts()" to set the counts
> prior to assigning the pointers.
> 
> Cc: codemender-patching+linux@google.com
> Assisted-by: LLM
> Signed-off-by: Bill Wendling <morbo@google.com>

I like this! Thanks!

Acked-by: Matti Vaittinen <mazziesaccount@gmail.com>

> ---
>   drivers/iio/industrialio-gts-helper.c |  4 ++--
>   include/linux/iio/iio-gts-helper.h    | 10 +++++-----
>   2 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iio/industrialio-gts-helper.c b/drivers/iio/industrialio-gts-helper.c
> index 4f52dc373abf..4de6324fd923 100644
> --- a/drivers/iio/industrialio-gts-helper.c
> +++ b/drivers/iio/industrialio-gts-helper.c
> @@ -652,10 +652,10 @@ static int iio_init_iio_gts(int max_scale_int, int max_scale_nano,
>   	if (ret)
>   		return ret;
>   
> -	gts->hwgain_table = gain_tbl;
>   	gts->num_hwgain = num_gain;
> -	gts->itime_table = tim_tbl;
> +	gts->hwgain_table = gain_tbl;
>   	gts->num_itime = num_times;
> +	gts->itime_table = tim_tbl;
>   
>   	return iio_gts_sanity_check(gts);
>   }
> diff --git a/include/linux/iio/iio-gts-helper.h b/include/linux/iio/iio-gts-helper.h
> index 66f830ab9b49..7e7d3396ff1a 100644
> --- a/include/linux/iio/iio-gts-helper.h
> +++ b/include/linux/iio/iio-gts-helper.h
> @@ -58,14 +58,14 @@ struct iio_itime_sel_mul {
>   
>   struct iio_gts {
>   	u64 max_scale;
> -	const struct iio_gain_sel_pair *hwgain_table;
> +	const struct iio_gain_sel_pair *hwgain_table __counted_by_ptr(num_hwgain);
>   	int num_hwgain;
> -	const struct iio_itime_sel_mul *itime_table;
> +	const struct iio_itime_sel_mul *itime_table __counted_by_ptr(num_itime);
>   	int num_itime;
> -	int **per_time_avail_scale_tables;
> -	int *avail_all_scales_table;
> +	int **per_time_avail_scale_tables __counted_by_ptr(num_itime);
> +	int *avail_all_scales_table __counted_by_ptr(num_avail_all_scales);
>   	int num_avail_all_scales;
> -	int *avail_time_tables;
> +	int *avail_time_tables __counted_by_ptr(num_avail_time_tables);
>   	int num_avail_time_tables;
>   };
>   


-- 
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

~~ When things go utterly wrong vim users can always type :help! ~~