Re: [PATCH] iio: imu: inv_icm42600: fix 64bit multiplication

[Antonio Quartulli <antonio@mandelbit.com>]

On 16/07/2025 21:36, Andy Shevchenko wrote:
> On Wed, Jul 16, 2025 at 10:22 PM Antonio Quartulli
> <antonio@mandelbit.com> wrote:
>>
>> In inv_icm42600_accel_convert_wom_to_roc() multiplying
>> `threshold` by `convert` may result in a number requiring more
>> than 32bit.
>> In this case, although `value` is 64bit wide, the result is
>> truncated because the multiplication is performed in the
>> 32bit domain, due to both operands being 32bit long.
>>
>> Cast the first operand to u64 to ensure the multiplication is
>> performed in the expected domain.
> 
> Is this a theoretical or practical issue?

Can't say if it's practical because I don't know how large `threshold` 
can be.

This said, `value` is declared as u64, therefore I assumed the result is 
expected to be potentially larger than 32 bits.

> 
>> Fixes: 50cfaa9a46c8 ("iio: imu: inv_icm42600: add WoM support")
> 
>> Address-Coverity-ID: 1647596 ("Integer handling issues (OVERFLOW_BEFORE_WIDEN)")
> 
> Is this tag now official? I can't find where it's documented.

I don't think it's official, but it's what I have found in the git 
history for other bugs reported by Coverity.
I already used it on other accepted patches as well.

Regards,

-- 
Antonio Quartulli

CEO and Co-Founder
Mandelbit Srl
https://www.mandelbit.com