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

[Ian Abbott]

On 2024-01-18 14:37, David Laight wrote:
> > -----Original Message-----
> > From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Sent: 18 January 2024 14:14
> > To: Denis Arefev <arefev@xxxxxxxxx>
> > Cc: Ian Abbott <abbotti@xxxxxxxxx>; H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>; linux-
> > kernel@xxxxxxxxxxxxxxx; lvc-project@xxxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx
> > Subject: Re: [PATCH] comedi: drivers: ni_tio: Fix arithmetic expression overflow
> >
> > On Thu, Jan 18, 2024 at 03:37:47PM +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.
> > >
> > > Fixes: 3e90b1c7ebe9 ("staging: comedi: ni_tio: tidy up ni_tio_set_clock_src() and helpers")
> > > Cc: <stable@xxxxxxxxxxxxxxx> # v5.15+
> > > Reviewed-by: Ian Abbott <abbotti@xxxxxxxxx>
> > > Signed-off-by: Denis Arefev <arefev@xxxxxxxxx>
> > > Signed-off-by: Ian Abbott <abbotti@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;
>
> What about 32bit systems...

Oh, good point.  It should be 1000ULL.

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