Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7;
Message-ID: <33441f01-d1a5-a6de-5e2b-364ac4ba8c31@embeddedor.com>
Date:   Sat, 23 Sep 2023 10:29:52 -0600
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.15.1
Subject: Re: [PATCH] input: mt: Annotate struct input_mt with __counted_by
Content-Language: en-US
To:     Kees Cook <keescook@chromium.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc:     linux-input@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: <20230922175036.work.762-kees@kernel.org>
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <20230922175036.work.762-kees@kernel.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 9/22/23 11:50, 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 input_mt.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: linux-input@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
-- 
Gustavo

> ---
>   include/linux/input/mt.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
> index 3b8580bd33c1..2cf89a538b18 100644
> --- a/include/linux/input/mt.h
> +++ b/include/linux/input/mt.h
> @@ -47,7 +47,7 @@ struct input_mt {
>   	unsigned int flags;
>   	unsigned int frame;
>   	int *red;
> -	struct input_mt_slot slots[];
> +	struct input_mt_slot slots[] __counted_by(num_slots);
>   };
>   
>   static inline void input_mt_set_value(struct input_mt_slot *slot,