[PATCH] drm/ttm: add a BUG_ON in ttm_set_driver_manager when array bounds

[Christian König]

Yeah, that's a good point.

If build_bug_on() doesn't works for some reason then we at least need to 
lower this to a WARN_ON.

A BUG_ON() is only justified if we prevent strong data corruption with 
it or note a NULL pointer earlier on or similar.

Regards,
Christian.

Am 10.09.21 um 06:36 schrieb Pan, Xinhui:
>
> [AMD Official Use Only]
>
>
> looks good to me.
> But maybe build_bug_on works too and more reasonable to detect such 
> wrong usage.
> ------------------------------------------------------------------------
> *From:* Chen, Guchun <Guchun.Chen at amd.com>
> *Sent:* Friday, September 10, 2021 12:30:14 PM
> *To:* amd-gfx at lists.freedesktop.org <amd-gfx at lists.freedesktop.org>; 
> dri-devel at lists.freedesktop.org <dri-devel at lists.freedesktop.org>; 
> Koenig, Christian <Christian.Koenig at amd.com>; Pan, Xinhui 
> <Xinhui.Pan at amd.com>; Deucher, Alexander <Alexander.Deucher at amd.com>
> *Cc:* Chen, Guchun <Guchun.Chen at amd.com>; Shi, Leslie 
> <Yuliang.Shi at amd.com>
> *Subject:* [PATCH] drm/ttm: add a BUG_ON in ttm_set_driver_manager 
> when array bounds
> 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.
>
> Signed-off-by: Leslie Shi <Yuliang.Shi at amd.com>
> Signed-off-by: Guchun Chen <guchun.chen at 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 7a0f561c57ee..24ad76ca8022 100644
> --- a/include/drm/ttm/ttm_device.h
> +++ b/include/drm/ttm/ttm_device.h
> @@ -308,6 +308,7 @@ 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)
>  {
> +       BUG_ON(type >= TTM_NUM_MEM_TYPES);
>          bdev->man_drv[type] = manager;
>  }
>
> -- 
> 2.17.1
>

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