RE: [PATCH][next] wifi: rtw89: coex: Fix __write_overflow_field error

[Ping-Ke Shih]

> -----Original Message-----
> From: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
> Sent: Wednesday, May 24, 2023 10:13 AM
> To: Ping-Ke Shih <pkshih@xxxxxxxxxxx>; Kalle Valo <kvalo@xxxxxxxxxx>
> Cc: linux-wireless@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Gustavo A. R. Silva
> <gustavoars@xxxxxxxxxx>; linux-hardening@xxxxxxxxxxxxxxx
> 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@xxxxxxxxxx>
> ---
>  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. 

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