[PATCH] drm/amdgpu: fix use-after-free issue

[Lazar, Lijo]

On 4/22/2024 4:52 PM, Christian König wrote:
> Am 22.04.24 um 11:37 schrieb Lazar, Lijo:
>>
>> On 4/22/2024 2:59 PM, Christian König wrote:
>>> Am 22.04.24 um 10:47 schrieb Jack Xiao:
>>>> Delete fence fallback timer to fix the ramdom
>>>> use-after-free issue.
>>> That's already done in amdgpu_fence_driver_hw_fini() and absolutely
>>> shouldn't be in amdgpu_ring_fini().
>>>
>>> And the kfree(ring->fence_drv.fences); shouldn't be there either since
>>> that is done in amdgpu_fence_driver_sw_fini().
>>>
>> In the present logic, these are part of special rings dynamically
>> created for mes self tests with
>> amdgpu_mes_add_ring/amdgpu_mes_remove_ring.
> 
> Ok, we should probably stop doing that altogether.
> 
> Shashanks work of utilizing the MES in userspace is nearly finished and
> we don't really need the MES test in the kernel any more.
> 

A v2 of the patch is posted. Can we use it temporarily till Shashank's
work is in place? Assuming Shashank's work will also include removing
MES self test in kernel.

Thanks,
Lijo

> Regards,
> Christian.
> 
>>
>> Thanks,
>> Lijo
>>
>>> Regards,
>>> Christian.
>>>
>>>> Signed-off-by: Jack Xiao <Jack.Xiao at amd.com>
>>>> ---
>>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c | 1 +
>>>>    1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>>>> index 06f0a6534a94..93ab9faa2d72 100644
>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>>>> @@ -390,6 +390,7 @@ void amdgpu_ring_fini(struct amdgpu_ring *ring)
>>>>                          &ring->gpu_addr,
>>>>                          (void **)&ring->ring);
>>>>        } else {
>>>> +        del_timer_sync(&ring->fence_drv.fallback_timer);
>>>>            kfree(ring->fence_drv.fences);
>>>>        }
>>>>    
>