Re: [PATCH] drm/amd/amdgpu/amdgpu_cs: fix refcount leak of a dma_fence obj

["Christian König" <christian.koenig@amd.com>]

Am 21.01.22 um 06:28 schrieb Xin Xiong:
> This issue takes place in an error path in
> amdgpu_cs_fence_to_handle_ioctl(). When `info->in.what` falls into
> default case, the function simply returns -EINVAL, forgetting to
> decrement the reference count of a dma_fence obj, which is bumped
> earlier by amdgpu_cs_get_fence(). This may result in reference count
> leaks.
>
> Fix it by decreasing the refcount of specific object before returning
> the error code.
>
> Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
> Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>

Good catch. Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index 0311d799a..894869789 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -1510,6 +1510,7 @@ int amdgpu_cs_fence_to_handle_ioctl(struct drm_device *dev, void *data,
>   		return 0;
>   
>   	default:
> +		dma_fence_put(fence);
>   		return -EINVAL;
>   	}
>   }