[PATCH] drm/komeda: return early if drm_universal_plane_init() fails.

[Carsten Haitzler]

On 12/3/21 14:15, Carsten Haitzler wrote:
> On 12/3/21 10:09, Liviu Dudau wrote:
>> If drm_universal_plane_init() fails early we jump to the common 
>> cleanup code
>> that calls komeda_plane_destroy() which in turn could access the 
>> uninitalised
>> drm_plane and crash. Return early if an error is detected without 
>> going through
>> the common code.
>>
>> Reported-by: Steven Price <steven.price at arm.com>
>> Signed-off-by: Liviu Dudau <liviu.dudau at arm.com>
>> ---
>>   drivers/gpu/drm/arm/display/komeda/komeda_plane.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_plane.c 
>> b/drivers/gpu/drm/arm/display/komeda/komeda_plane.c
>> index aa193c58f4bf6d9..517b94c3bcaf966 100644
>> --- a/drivers/gpu/drm/arm/display/komeda/komeda_plane.c
>> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_plane.c
>> @@ -279,8 +279,10 @@ static int komeda_plane_add(struct komeda_kms_dev 
>> *kms,
>>       komeda_put_fourcc_list(formats);
>> -    if (err)
>> -        goto cleanup;
>> +    if (err) {
>> +        kfree(kplane);
>> +        return err;
>> +    }
>>       drm_plane_helper_add(plane, &komeda_plane_helper_funcs);
>>
> 
> Ummm... can I disagree here? this goto cleanup I think is just fine 
> because plane has been set before drm_universal_plane_init() is called 
> which is before the if (err) here. komeda_plane_destroy() in cleanup: 
> does all the right things, so this patch isn't needed. I think it's less 
> clean as it adds a new "handle error" path special-case instance where a 
> special case is not needed. The fix to Zhou's original patch was needed 
> for exactly the reason Liviu said - but not this one... ?

Let me take that back - it seems an init fail shouldn't call cleanup but 
the init fail doesn't quite cleanup properly. Steven found this and 
already sent a patch.