2024-01-17 12:53:17

by Denis Arefev

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

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.

Signed-off-by: Denis Arefev <[email protected]>
---
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;
ni_tio_set_sync_mode(counter);
return 0;
}
--
2.25.1

2024-01-17 16:22:58

by Ian Abbott

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

On 17/01/2024 12:42, 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.
>
> Signed-off-by: Denis Arefev <[email protected]>
> ---
> 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;
> ni_tio_set_sync_mode(counter);
> return 0;
> }

Looks good, thanks!

Reviewed-by: Ian Abbott <[email protected]>

Could you resend it and Cc Greg Kroah-Hartman
<[email protected]> ? It's more likely to get applied that way
because I don't maintain my own kernel tree for comedi. Feel free to
add my Reviewed-by line.

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