Re: [PATCH] drm/i915/gvt: don't dereference 'workload' before null checking it

[Colin Ian King]

On 21/03/18 19:23, Chris Wilson wrote:
> Quoting Colin Ian King (2018-03-21 19:18:28)
>> On 21/03/18 19:09, Joe Perches wrote:
>>> On Wed, 2018-03-21 at 19:06 +0000, Colin King wrote:
>>>> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>>>
>>>> The pointer workload is dereferenced before it is null checked, hence
>>>> there is a potential for a null pointer dereference on workload. Fix
>>>> this by only dereferencing workload after it is null checked.
>>>>
>>>> Detected by CoverityScan, CID#1466017 ("Dereference before null check")
>>>
>>> Maybe true, but is it possible for workload to be null?
>>> Maybe the null test should be removed instead.
>>
>> From what I understand from the static analysis, there may be a
>> potential for workload to be null, I couldn't rule it out so I went with
>> the more paranoid stance of keeping the null check in.
> 
> Not sr_oa_regs() problem if workload is NULL, that's the callers. I
> reviewed the identical patch yesterday, and we ended up with removing
> the NULL checks, just keeping the workload->id != RCS.
> -Chris
> 
Ah, OK, thanks for the clarification Chris.