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Date:   Sat, 23 Sep 2023 10:57:47 -0600
From:   "Gustavo A. R. Silva" <gustavoars@kernel.org>
To:     Kees Cook <keescook@chromium.org>
Cc:     Maximilian Luz <luzmaximilian@gmail.com>,
        platform-driver-x86@vger.kernel.org,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] platform/surface: aggregator: Annotate struct ssam_event
 with __counted_by
Message-ID: <ZQ8ZCyoospgceCHv@work>
References: <20230922175436.work.031-kees@kernel.org>
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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@gmail.com>
> Cc: platform-driver-x86@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

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
> 
>