[PATCH] drm/amdgpu: fix dereference null return value for the function amdgpu_vm_pt_parent

[Christian König]

Am 23.05.24 um 08:13 schrieb Jesse Zhang:
> The pointer parent may be NULLed by the function amdgpu_vm_pt_parent.
> To make the code more robust, check the pointer parent.

No that doesn't make any sense.

When parent is NULL here we should probably call BUG() instead.

Regards,
Christian.

>
> Signed-off-by: Jesse Zhang <Jesse.Zhang at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
> index 0763382d305a..bad8d2c31202 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
> @@ -706,11 +706,15 @@ int amdgpu_vm_pde_update(struct amdgpu_vm_update_params *params,
>   			 struct amdgpu_vm_bo_base *entry)
>   {
>   	struct amdgpu_vm_bo_base *parent = amdgpu_vm_pt_parent(entry);
> -	struct amdgpu_bo *bo = parent->bo, *pbo;
> +	struct amdgpu_bo *bo, *pbo;
>   	struct amdgpu_vm *vm = params->vm;
>   	uint64_t pde, pt, flags;
>   	unsigned int level;
>   
> +	if (!parent)
> +		return -EINVAL;
> +	bo = parent->bo;
> +
>   	for (level = 0, pbo = bo->parent; pbo; ++level)
>   		pbo = pbo->parent;
>