drm/amd/amdgpu: Check tbo resource pointer

Validate tbo resource pointer, skip if NULL
Signed-off-by: Asad Kamal <asad.kamal@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -5012,7 +5012,8 @@ static int amdgpu_device_recover_vram(struct amdgpu_device *adev)
 		shadow = vmbo->shadow;
 
 		/* No need to recover an evicted BO */
-		if (shadow->tbo.resource->mem_type != TTM_PL_TT ||
+		if (!shadow->tbo.resource ||
+		    shadow->tbo.resource->mem_type != TTM_PL_TT ||
 		    shadow->tbo.resource->start == AMDGPU_BO_INVALID_OFFSET ||
 		    shadow->parent->tbo.resource->mem_type != TTM_PL_VRAM)
 			continue;