Re: [PATCH] iio: stx104: Store channel output state values as int

From: William Breathitt Gray
Date: Mon Jul 25 2016 - 08:41:35 EST


On Sun, Jul 24, 2016 at 02:06:49PM +0100, Jonathan Cameron wrote:
>On 13/07/16 15:43, William Breathitt Gray wrote:
>> The val parameter has a data type of int in the read_raw and write_raw
>> callbacks. The chan_out_states array should have elements of type int in
>> order to match the data type of the val parameter.
>>
>> This patch fixes a possible integer overflow condition when the the int
>> pointer val is dereferenced to store the unsigned int chan_out_states
>> element in the read_raw callback.
>>
>> Fixes: 97a445dad37a ("iio: Add IIO support for the DAC on the Apex Embedded Systems STX104")
>> Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
>Isn't this only a problem if an out of range value was written
>in the first place? The values it'll take are only 16bits,
>so a simple range check around that would fix the root problem.
>
>J

Please disregard this patch.

When I submitted this patch I had assumed the possibility of platforms
with 16-bit int; if all platforms supported by the Linux kernel have at
minimum 32-bit int, then a simple range check should be sufficient.

William Breathitt Gray

>> ---
>> drivers/iio/dac/stx104.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c
>> index 792a971..b22b744 100644
>> --- a/drivers/iio/dac/stx104.c
>> +++ b/drivers/iio/dac/stx104.c
>> @@ -47,7 +47,7 @@ MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
>> * @base: base port address of the IIO device
>> */
>> struct stx104_iio {
>> - unsigned chan_out_states[STX104_NUM_CHAN];
>> + int chan_out_states[STX104_NUM_CHAN];
>> unsigned base;
>> };
>>
>>
>