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Date: Wed, 9 Aug 2023 14:28:27 +0200
From: Simon Horman <horms@kernel.org>
To: "GONG, Ruiqi" <gongruiqi@huaweicloud.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>,
	Jozsef Kadlecsik <kadlec@netfilter.org>,
	Florian Westphal <fw@strlen.de>, Roopa Prabhu <roopa@nvidia.com>,
	Nikolay Aleksandrov <razor@blackwall.org>,
	Kees Cook <keescook@chromium.org>,
	"Gustavo A . R . Silva" <gustavoars@kernel.org>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	netdev@vger.kernel.org, linux-hardening@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Wang Weiyang <wangweiyang2@huawei.com>,
	Xiu Jianfeng <xiujianfeng@huawei.com>, gongruiqi1@huawei.com
Subject: Re: [PATCH v3] netfilter: ebtables: fix fortify warnings in
 size_entry_mwt()
Message-ID: <ZNOGa02ymvkTAXPD@vergenet.net>
References: <20230809074503.1323102-1-gongruiqi@huaweicloud.com>
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In-Reply-To: <20230809074503.1323102-1-gongruiqi@huaweicloud.com>

On Wed, Aug 09, 2023 at 03:45:03PM +0800, GONG, Ruiqi wrote:
> From: "GONG, Ruiqi" <gongruiqi1@huawei.com>
> 
> When compiling with gcc 13 and CONFIG_FORTIFY_SOURCE=y, the following
> warning appears:
> 
> In function ‘fortify_memcpy_chk’,
>     inlined from ‘size_entry_mwt’ at net/bridge/netfilter/ebtables.c:2118:2:
> ./include/linux/fortify-string.h:592:25: error: call to ‘__read_overflow2_field’
> declared with attribute warning: detected read beyond size of field (2nd parameter);
> maybe use struct_group()? [-Werror=attribute-warning]
>   592 |                         __read_overflow2_field(q_size_field, size);
>       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> The compiler is complaining:
> 
> memcpy(&offsets[1], &entry->watchers_offset,
>                        sizeof(offsets) - sizeof(offsets[0]));
> 
> where memcpy reads beyong &entry->watchers_offset to copy

nit: beyong -> beyond

...