diff mbox series

comedi: drivers: ni_tio: Fix arithmetic expression overflow

Message ID 20240118073619.40538-1-arefev@swemel.ru
State New
Headers
Series comedi: drivers: ni_tio: Fix arithmetic expression overflow |

Commit Message

Denis Arefev Jan. 18, 2024, 7:36 a.m. UTC 
  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@mev.co.uk>
Signed-off-by: Denis Arefev <arefev@swemel.ru>
---
 drivers/comedi/drivers/ni_tio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Greg KH Jan. 18, 2024, 9:32 a.m. UTC | #1 
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@mev.co.uk>
> Signed-off-by: Denis Arefev <arefev@swemel.ru>
> ---
>  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
Ian Abbott Jan. 18, 2024, 11:11 a.m. UTC | #2 
On 18/01/2024 09:32, Greg Kroah-Hartman wrote:
> 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@mev.co.uk>
>> Signed-off-by: Denis Arefev <arefev@swemel.ru>
>> ---
>>   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?

The period_ns value comes from user-space and could be any unsigned int 
value.  It's used to let the driver know the period of an external clock 
source.

> And what commit id does this fix?

Fixes: 3e90b1c7ebe9 ("staging: comedi: ni_tio: tidy up 
ni_tio_set_clock_src() and helpers")
Cc: <stable@vger.kernel.org> # v5.15+

The first affected kernel version is v3.17.  This patch should apply 
cleanly to v5.13 onwards (when comedi was moved out of drivers/staging), 
but earlier stable/longterm kernels would require a backported patch.

@Denis, if you could add the above Fixes: and Cc: lines to a v2 patch, 
that would be great!

> 
> thanks,
> 
> greg k-h
diff mbox series

Patch

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;
 }