Re: [PATCH 8/9] drm/vmwgfx: Annotate struct vmw_surface_dirty with __counted_by

[Gustavo A. R. Silva]

On 9/22/23 11:32, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct vmw_surface_dirty.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Zack Rusin <zackr@xxxxxxxxxx>
> Cc: VMware Graphics Reviewers <linux-graphics-maintainer@xxxxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>

Thanks
--
Gustavo


> ---
>   drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> index 5db403ee8261..2d1d857f99ae 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> @@ -77,7 +77,7 @@ struct vmw_surface_offset {
>   struct vmw_surface_dirty {
>   	struct vmw_surface_cache cache;
>   	u32 num_subres;
> -	SVGA3dBox boxes[];
> +	SVGA3dBox boxes[] __counted_by(num_subres);
>   };
>   
>   static void vmw_user_surface_free(struct vmw_resource *res);