Re: [patch] drm/amdgpu: potential NULL dereference on error

[walter harms <wharms@bfs.de>]

Am 11.06.2015 14:20, schrieb Dan Carpenter:
> On Thu, Jun 11, 2015 at 02:03:18PM +0200, walter harms wrote:
>>
>>
>> Am 11.06.2015 10:49, schrieb Dan Carpenter:
>>> debugfs_create_file() can return an error pointer if debugfs is disabled
>>> or it can return NULL on error.
>>>
>>> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> index 36be03c..adba2a1 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> @@ -1980,6 +1980,8 @@ static int amdgpu_debugfs_regs_init(struct amdgpu_device *adev)
>>>  				  adev, &amdgpu_debugfs_regs_fops);
>>>  	if (IS_ERR(ent))
>>>  		return PTR_ERR(ent);
>>> +	if (!ent)
>>> +		return -ENOMEM;
>>>  	i_size_write(ent->d_inode, adev->rmmio_size);
>>>  	adev->debugfs_regs = ent;
>>
>>
>>
>> would  PTR_ERR_OR_ZERO() by an option ?
>>
>> on the other hand,
>> why does debugfs_create_file() does not return -ENOMEN instead of NULL ?
>>
> 
> Actually if debugfs is disabled then we should probably carry on.  Let
> me change it to:
> 
> 	if (IS_ERR(ent))
> 		return 0;
> 
> 	if (!ent)
> 		return -ENOMEM;
> 

You still have to check 2 types of error return here.
I simply do not understand why ebugfs_create_file() does not return -ENOMEM
(or returns NULL on any error).

re,
 wh