Re: [PATCH] platform/surface: aggregator: Annotate struct ssam_event with __counted_by

[Gustavo A. R. Silva]

On Fri, Sep 22, 2023 at 10:54:37AM -0700, 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 ssam_event.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Maximilian Luz <luzmaximilian@xxxxxxxxx>
> Cc: platform-driver-x86@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

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

Thanks
--
Gustavo

> ---
>  include/linux/surface_aggregator/controller.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/surface_aggregator/controller.h b/include/linux/surface_aggregator/controller.h
> index cb7980805920..5b67f0f47d80 100644
> --- a/include/linux/surface_aggregator/controller.h
> +++ b/include/linux/surface_aggregator/controller.h
> @@ -44,7 +44,7 @@ struct ssam_event {
>  	u8 command_id;
>  	u8 instance_id;
>  	u16 length;
> -	u8 data[];
> +	u8 data[] __counted_by(length);
>  };
>  
>  /**
> -- 
> 2.34.1
> 
>