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Message-ID: <e326ed06-3f72-4552-a26d-5deae0678409@gmail.com>
Date:   Sun, 24 Sep 2023 13:48:26 +0200
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User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] platform/surface: aggregator: Annotate struct ssam_event
 with __counted_by
Content-Language: en-US
To:     Kees Cook <keescook@chromium.org>
Cc:     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
References: <20230922175436.work.031-kees@kernel.org>
From:   Maximilian Luz <luzmaximilian@gmail.com>
In-Reply-To: <20230922175436.work.031-kees@kernel.org>
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On 9/22/23 19:54, 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>
> ---
>   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);
>   };
>   
>   /**

Thanks!

Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>