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Message-ID: <13a74848-d961-7424-da7e-2bb7b904e899@embeddedor.com>
Date:   Tue, 23 May 2023 20:31:36 -0600
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Subject: Re: [PATCH][next] wifi: rtw89: coex: Fix __write_overflow_field error
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To:     Ping-Ke Shih <pkshih@realtek.com>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Kalle Valo <kvalo@kernel.org>
Cc:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-hardening@vger.kernel.org" <linux-hardening@vger.kernel.org>
References: <ZG1ynqdAnXArMfBE@work>
 <b45c71d19add4f749a687e5ca483244b@realtek.com>
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <b45c71d19add4f749a687e5ca483244b@realtek.com>
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On 5/23/23 20:21, Ping-Ke Shih wrote:
> 
> 
>> -----Original Message-----
>> From: Gustavo A. R. Silva <gustavoars@kernel.org>
>> Sent: Wednesday, May 24, 2023 10:13 AM
>> To: Ping-Ke Shih <pkshih@realtek.com>; Kalle Valo <kvalo@kernel.org>
>> Cc: linux-wireless@vger.kernel.org; linux-kernel@vger.kernel.org; Gustavo A. R. Silva
>> <gustavoars@kernel.org>; linux-hardening@vger.kernel.org
>> Subject: [PATCH][next] wifi: rtw89: coex: Fix __write_overflow_field error
>>
>> One-element arrays as fake flexible arrays are deprecated, and we are
>> moving towards adopting C99 flexible-array members instead.
>>
>> Fix the following error seen under GCC-13 and -fstrict-flex-arrays=3:
>> In function ‘fortify_memcpy_chk’,
>>      inlined from ‘_append_tdma’ at drivers/net/wireless/realtek/rtw89/coex.c:1579:3:
>> include/linux/fortify-string.h:583:25: error: call to ‘__write_overflow_field’ declared with attribute
>> warning: detected write beyond size of field (1st parameter); maybe use struct_group()?
>> [-Werror=attribute-warning]
>>    583 |                         __write_overflow_field(p_size_field, size);
>>        |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
>> routines on memcpy() and help us make progress towards globally
>> enabling -fstrict-flex-arrays=3 [1].
>>
>> This results in no differences in binary output.
>>
>> Link: https://github.com/KSPP/linux/issues/21
>> Link: https://github.com/KSPP/linux/issues/299
>> Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>> ---
>>   drivers/net/wireless/realtek/rtw89/coex.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/realtek/rtw89/coex.c b/drivers/net/wireless/realtek/rtw89/coex.c
>> index 3a586a971e8f..bda0e1e99a8c 100644
>> --- a/drivers/net/wireless/realtek/rtw89/coex.c
>> +++ b/drivers/net/wireless/realtek/rtw89/coex.c
>> @@ -206,7 +206,7 @@ static const struct rtw89_btc_ver rtw89_btc_ver_defs[] = {
>>   struct rtw89_btc_btf_tlv {
>>          u8 type;
>>          u8 len;
>> -       u8 val[1];
>> +       u8 val[];
>>   } __packed;
>>
>>   enum btc_btf_set_report_en {
> 
> Arnd has sent the same patch [1] as yours.

Oh that's great! What a coincidence. :)

Thanks for letting me know.
--
Gustavo

> 
> [1] https://lore.kernel.org/linux-wireless/27a7010de8be4006a3e4b95e851781c6@realtek.com/T/#mca619c8261b87b88eedd391ceafb34c40d513ce5
>