linux-hardening - Re: [PATCH] input: Annotate struct evdev_client with __counted

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Date: Sat, 23 Sep 2023 10:29:03 -0600
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Kees Cook <keescook@...omium.org>,
 Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: linux-input@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>,
 Nick Desaulniers <ndesaulniers@...gle.com>, Tom Rix <trix@...hat.com>,
 linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH] input: Annotate struct evdev_client with __counted_by



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 evdev_client.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> Cc: linux-input@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>

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

Thanks
-- 
Gustavo

> ---
>   drivers/input/evdev.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> index 95f90699d2b1..51e0c4954600 100644
> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -50,7 +50,7 @@ struct evdev_client {
>   	bool revoked;
>   	unsigned long *evmasks[EV_CNT];
>   	unsigned int bufsize;
> -	struct input_event buffer[];
> +	struct input_event buffer[] __counted_by(bufsize);
>   };
>   
>   static size_t evdev_get_mask_cnt(unsigned int type)