[PATCH] iio: adc: ti_am335x_adc: Limit step_avg to valid range for gcc complains

[Pei Xiao]

On 11/28/24 08:45, Pei Xiao wrote:
>> at91_adc_interrupt can call at91_adc_touch_data_handler function
>> to start the work by schedule_work(&st->touch_st.workq).
>> 
>> If we remove the module which will call at91_adc_remove to
>> make cleanup, it will free indio_dev through iio_device_unregister
>> while the work mentioned above will be used. The sequence of operations
>> that may lead to a UAF bug is as follows:
>> 
>> CPU0                                      CPU1
> 
>                                      | at91_adc_workq_handler
>> at91_adc_remove                      |
>> iio_device_unregister(indio_dev)     |
>> device_release                       |
>> //free indio_dev                     |
>                                      | iio_push_to_buffers(indio_dev)
>                                      | //use indio_dev
> 
> Fix it by ensuring that the work is canceled before proceeding with
> the cleanup in at91_adc_remove.
>> 
>> Fixes: 27e177190891 ("iio:adc:at91_adc8xx: introduce new atmel adc driver")

>I believe that the commit that introduced the workqueue is different
>than the one you tagged here.

>With that changed,

>Reviewed-by: Eugen Hristev <eugen.hristev at linaro.org>

I am so sorry I have been ignoring this reply for almost a year..

>> Signed-off-by: Pei Xiao <xiaopei01 at kylinos.cn>
>> ---
>>  drivers/iio/adc/at91-sama5d2_adc.c | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
>> index 8e5aaf15a921..4ba52b500054 100644
>> --- a/drivers/iio/adc/at91-sama5d2_adc.c
>> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
>> @@ -2491,6 +2491,7 @@ static void at91_adc_remove(struct platform_device *pdev)
>>  	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>>  	struct at91_adc_state *st = iio_priv(indio_dev);
>>  
>> +	cancel_work_sync(&st->touch_st.workq);
>>  	iio_device_unregister(indio_dev);
>>  
>>  	at91_adc_dma_disable(st);