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Date:   Sat, 23 Sep 2023 10:38:11 -0600
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Subject: Re: [PATCH] watch_queue: Annotate struct watch_filter with
 __counted_by
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To:     Kees Cook <keescook@chromium.org>,
        David Howells <dhowells@redhat.com>
Cc:     Randy Dunlap <rdunlap@infradead.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Siddh Raman Pant <code@siddh.me>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Qian Cai <cai@redhat.com>,
        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: <20230922175407.work.754-kees@kernel.org>
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <20230922175407.work.754-kees@kernel.org>
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On 9/22/23 11:54, 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 watch_filter.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: David Howells <dhowells@redhat.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Siddh Raman Pant <code@siddh.me>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: Qian Cai <cai@redhat.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
-- 
Gustavo

> ---
>   include/linux/watch_queue.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/watch_queue.h b/include/linux/watch_queue.h
> index 45cd42f55d49..429c7b6afead 100644
> --- a/include/linux/watch_queue.h
> +++ b/include/linux/watch_queue.h
> @@ -32,7 +32,7 @@ struct watch_filter {
>   		DECLARE_BITMAP(type_filter, WATCH_TYPE__NR);
>   	};
>   	u32			nr_filters;	/* Number of filters */
> -	struct watch_type_filter filters[];
> +	struct watch_type_filter filters[] __counted_by(nr_filters);
>   };
>   
>   struct watch_queue {