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Message-ID: <ec1ae7b4-6563-b4ec-7eff-b1dd29d9ba8e@embeddedor.com>
Date:   Wed, 4 Oct 2023 01:36:04 +0200
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Subject: Re: [PATCH] nexthop: Annotate struct nh_res_table with __counted_by
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To:     Kees Cook <keescook@chromium.org>, David Ahern <dsahern@kernel.org>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org, llvm@lists.linux.dev
References: <20231003231813.work.042-kees@kernel.org>
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <20231003231813.work.042-kees@kernel.org>
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On 10/4/23 01:18, 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 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 nh_res_table.
> 
> Cc: David Ahern <dsahern@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org
> Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
--
Gustavo

> ---
>   include/net/nexthop.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/net/nexthop.h b/include/net/nexthop.h
> index 5dc4b4bba8a5..09f9a732e640 100644
> --- a/include/net/nexthop.h
> +++ b/include/net/nexthop.h
> @@ -92,7 +92,7 @@ struct nh_res_table {
>   	u32			unbalanced_timer;
>   
>   	u16			num_nh_buckets;
> -	struct nh_res_bucket	nh_buckets[];
> +	struct nh_res_bucket	nh_buckets[] __counted_by(num_nh_buckets);
>   };
>   
>   struct nh_grp_entry {