Re: [PATCH v4 8/9] s390/vfio-ap: Fix NULL deref in status_show() during queue probe

>>
>> Do you think adding an additional NULL check against dev_get_drvdata()
>> in status_show() and treating the NULL case like the other error
>> conditions would be enough to cover that window?
> 
> It would cover that window, but that function does not return any error, so
> we'd have to decide what makes the most sense between the following
> three values, or create new one to indicate we don't know the status.
> 
> AP_QUEUE_ASSIGNED
> AP_QUEUE_UNASSIGNED
> AP_QUEUE_IN_USE
> 

If there's no drvdata then it can't be assigned, right?  So maybe
AP_QUEUE_UNASSIGNED?  Unless you can think of a reason it would not work?