diff mbox series

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

Message ID 20210910043014.529-1-guchun.chen@amd.com (mailing list archive)
State New, archived
Headers show
Series drm/ttm: add a BUG_ON in ttm_set_driver_manager when array bounds | expand

Commit Message

Chen, Guchun Sept. 10, 2021, 4:30 a.m. UTC 
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@amd.com>
Signed-off-by: Guchun Chen <guchun.chen@amd.com>
---
 include/drm/ttm/ttm_device.h | 1 +
 1 file changed, 1 insertion(+)

Comments

Pan, Xinhui Sept. 10, 2021, 4:36 a.m. UTC | #1 
[AMD Official Use Only]

looks good to me.
But maybe build_bug_on works too and more reasonable to detect such wrong usage.
Christian König Sept. 10, 2021, 6:36 a.m. UTC | #2 
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@amd.com>
> *Sent:* Friday, September 10, 2021 12:30:14 PM
> *To:* amd-gfx@lists.freedesktop.org <amd-gfx@lists.freedesktop.org>; 
> dri-devel@lists.freedesktop.org <dri-devel@lists.freedesktop.org>; 
> Koenig, Christian <Christian.Koenig@amd.com>; Pan, Xinhui 
> <Xinhui.Pan@amd.com>; Deucher, Alexander <Alexander.Deucher@amd.com>
> *Cc:* Chen, Guchun <Guchun.Chen@amd.com>; Shi, Leslie 
> <Yuliang.Shi@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@amd.com>
> Signed-off-by: Guchun Chen <guchun.chen@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
>
Chen, Guchun Sept. 10, 2021, 8:46 a.m. UTC | #3 
[Public]

Hi Christian and Xinhui,

Thanks for your suggestion. The cause is I saw data corruption in several proprietary use cases. BUILD_BUG_ON will have build variation per gcc difference?

Anyway, WARN_ON is fine to me, and I will send a new patch set soon to address this.

Regards,
Guchun

From: Koenig, Christian <Christian.Koenig@amd.com>
Sent: Friday, September 10, 2021 2:37 PM
To: Pan, Xinhui <Xinhui.Pan@amd.com>; amd-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; Deucher, Alexander <Alexander.Deucher@amd.com>; Chen, Guchun <Guchun.Chen@amd.com>
Cc: Shi, Leslie <Yuliang.Shi@amd.com>
Subject: Re: [PATCH] drm/ttm: add a BUG_ON in ttm_set_driver_manager when array bounds

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.
diff mbox series

Patch

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;
 }