Re: [PATCH] iio: invensense: fix integer overflow while multiplication

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 03 Nov 2024 08:43:14 +0000
Karan Sanghavi <karansanghvi98@gmail.com> wrote:

Hi Karan,

> Typecast a variable to int64_t for 64-bit arithmetic multiplication

The path to actually triggering this is non obvious as these
inputs are the result of rather complex code paths and per chip
constraints.  Have you identified a particular combination that overflows
or is this just based on the type?  I have no problem with applying this
as hardening against future uses but unless we have a path to trigger
it today it isn't a fix.

If you do have a path, this description should state what it is.

> 
> Signed-off-by: Karan Sanghavi <karansanghvi98@gmail.com>
If it's a real bug, needs a Fixes tag so we know how far to backport it.

> ---
>  drivers/iio/common/inv_sensors/inv_sensors_timestamp.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/common/inv_sensors/inv_sensors_timestamp.c b/drivers/iio/common/inv_sensors/inv_sensors_timestamp.c
> index f44458c380d9..d1d11d0b2458 100644
> --- a/drivers/iio/common/inv_sensors/inv_sensors_timestamp.c
> +++ b/drivers/iio/common/inv_sensors/inv_sensors_timestamp.c
> @@ -105,8 +105,8 @@ static bool inv_update_chip_period(struct inv_sensors_timestamp *ts,
>  
>  static void inv_align_timestamp_it(struct inv_sensors_timestamp *ts)
>  {
> -	const int64_t period_min = ts->min_period * ts->mult;
> -	const int64_t period_max = ts->max_period * ts->mult;
> +	const int64_t period_min = (int64_t)ts->min_period * ts->mult;
> +	const int64_t period_max = (int64_t)ts->max_period * ts->mult;
>  	int64_t add_max, sub_max;
>  	int64_t delta, jitter;
>  	int64_t adjust;
> 
> ---
> base-commit: 81983758430957d9a5cb3333fe324fd70cf63e7e
> change-id: 20241102-coverity1586045integeroverflow-cbbf357475d9
> 
> Best regards,