[PATCH] drm/amdgpu: disallow multiple BO_HANDLES chunks in one submit

[Pierre-Eric Pelloux-Prayer]

Le 02/07/2024 à 15:35, Christian König a écrit :
> Am 02.07.24 um 15:23 schrieb Pierre-Eric Pelloux-Prayer:
>> Before this commit, only submits with both a BO_HANDLES chunk and a
>> 'bo_list_handle' would be rejected (by amdgpu_cs_parser_bos).
>>
>> But if UMD sent a multiple BO_HANDLES, what would happen is:
>> * only the last one would be really used
>> * all the others would leak memory as amdgpu_cs_p1_bo_handles would
>>    overwrite the previous p->bo_list value
>>
>> This commit rejects submissions with multiple BO_HANDLES chunks to
>> match the implementation of the parser.
>>
>> Signed-off-by: Pierre-Eric Pelloux-Prayer 
>> <pierre-eric.pelloux-prayer at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> index c08dfffae262..69d168d6f35a 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -154,6 +154,10 @@ static int amdgpu_cs_p1_bo_handles(struct 
>> amdgpu_cs_parser *p,
>>       struct drm_amdgpu_bo_list_entry *info;
>>       int r;
>> +    /* Disallow multiple BO_HANDLES chunks. */
> 
> Describe why you do something, instead of what you do since that should 
> be obvious from the code.
> 
> E.g. something like /* Only allow a single BO list to avoid memory leak. */

It's not really to avoid a memleak because the code below could be fixed
to not leak the list.
This change is really about only disallowing multiple BO_HANDLES since 
this is the de-facto API, except it was not validated until now.

I can rephrase the comment as /* Only a single BO list is allowed. */

Would that work?

Thanks,
Pierre-Eric

> 
> With that fixed Reviewed-by: Christian König <christian.koenig at amd.com>
> 
> Regards,
> Christian.
> 
> 
>> +    if (p->bo_list)
>> +        return -EINVAL;
>> +
>>       r = amdgpu_bo_create_list_entry_array(data, &info);
>>       if (r)
>>           return r;