Re: [PATCH] drm/ttm: add a WARN_ON in ttm_set_driver_manager when array bounds (v2)

[Robin Murphy]

On 2021-09-10 11:09, Guchun Chen wrote:
Vendor will define their own memory types on top of TTM_PL_PRIV,
but call ttm_set_driver_manager directly without checking mem_type
value when setting up memory manager. So add such check to aware
the case when array bounds.
v2: lower check level to WARN_ON

Signed-off-by: Leslie Shi <yuliang....@amd.com>
Signed-off-by: Guchun Chen <guchun.c...@amd.com>
---
  include/drm/ttm/ttm_device.h | 1 +
  1 file changed, 1 insertion(+)

diff --git a/include/drm/ttm/ttm_device.h b/include/drm/ttm/ttm_device.h
index 07d722950d5b..aa79953c807c 100644
--- a/include/drm/ttm/ttm_device.h
+++ b/include/drm/ttm/ttm_device.h
@@ -291,6 +291,7 @@ ttm_manager_type(struct ttm_device *bdev, int mem_type)
  static inline void ttm_set_driver_manager(struct ttm_device *bdev, int type,
                                          struct ttm_resource_manager *manager)
  {
+       WARN_ON(type >= TTM_NUM_MEM_TYPES);

Nit: I know nothing about this code, but from the context alone it would 
seem sensible to do

        if (WARN_ON(type >= TTM_NUM_MEM_TYPES))
                return;

to avoid making the subsequent assignment when we *know* it's invalid 
and likely to corrupt memory.

Robin.

        bdev->man_drv[type] = manager;
  }