Re: [PATCH] comedi: drivers: ni_tio: Fix arithmetic expression overflow

[Greg Kroah-Hartman]

On Thu, Jan 18, 2024 at 10:36:19AM +0300, Denis Arefev wrote:
> The value of an arithmetic expression period_ns * 1000 is subject
> to overflow due to a failure to cast operands to a larger data
> type before performing arithmetic
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Reviewed-by: Ian Abbott <abbotti@xxxxxxxxx>
> Signed-off-by: Denis Arefev <arefev@xxxxxxxxx>
> ---
>  drivers/comedi/drivers/ni_tio.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/comedi/drivers/ni_tio.c b/drivers/comedi/drivers/ni_tio.c
> index da6826d77e60..acc914903c70 100644
> --- a/drivers/comedi/drivers/ni_tio.c
> +++ b/drivers/comedi/drivers/ni_tio.c
> @@ -800,7 +800,7 @@ static int ni_tio_set_clock_src(struct ni_gpct *counter,
>  				GI_PRESCALE_X2(counter_dev->variant) |
>  				GI_PRESCALE_X8(counter_dev->variant), bits);
>  	}
> -	counter->clock_period_ps = period_ns * 1000;
> +	counter->clock_period_ps = period_ns * 1000UL;

Can period_ns ever be "too big" to cause such an overflow?

And what commit id does this fix?

thanks,

greg k-h