wifi: rtw89: coex: Fix -Wstringop-overflow warnings in _append_tdma()

Copy a couple of structures directly, instead of using memcpy().

This addesses the following -Wstringop-overflow warnings:
drivers/net/wireless/realtek/rtw89/coex.c: In function ‘_append_tdma’:
./include/linux/fortify-string.h:57:33: warning: writing 8 bytes into a region of size 0 [-Wstringop-overflow=]

   57 | #define __underlying_memcpy     __builtin_memcpy
      |                                 ^
./include/linux/fortify-string.h:644:9: note: in expansion of macro ‘__underlying_memcpy’
  644 |         __underlying_##op(p, q, __fortify_size);                        \
      |         ^~~~~~~~~~~~~
./include/linux/fortify-string.h:689:26: note: in expansion of macro ‘__fortify_memcpy_chk’
  689 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,                  \
      |                          ^~~~~~~~~~~~~~~~~~~~
drivers/net/wireless/realtek/rtw89/coex.c:1585:17: note: in expansion of macro ‘memcpy’
 1585 |                 memcpy(&v3->tdma, &dm->tdma, sizeof(v3->tdma));
      |                 ^~~~~~

drivers/net/wireless/realtek/rtw89/core.h:2703:37: note: at offset [5714, 71249] into destination object ‘ver’ of size 8
2703 | const struct rtw89_btc_ver *ver;
| ^~~
./include/linux/fortify-string.h:57:33: warning: writing 8 bytes into a region of size 0 [-Wstringop-overflow=]

   57 | #define __underlying_memcpy     __builtin_memcpy
      |                                 ^
./include/linux/fortify-string.h:644:9: note: in expansion of macro ‘__underlying_memcpy’
  644 |         __underlying_##op(p, q, __fortify_size);                        \
      |         ^~~~~~~~~~~~~
./include/linux/fortify-string.h:689:26: note: in expansion of macro ‘__fortify_memcpy_chk’
  689 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,                  \
      |                          ^~~~~~~~~~~~~~~~~~~~
drivers/net/wireless/realtek/rtw89/coex.c:1579:17: note: in expansion of macro ‘memcpy’
 1579 |                 memcpy(v, &dm->tdma, sizeof(*v));
      |                 ^~~~~~

drivers/net/wireless/realtek/rtw89/core.h:2703:37: note: at offset [5710, 71245] into destination object ‘ver’ of size 8
2703 | const struct rtw89_btc_ver *ver;
| ^~~

This helps with the ongoing efforts to globally enable -Wstringop-overflow.

---
 drivers/net/wireless/realtek/rtw89/coex.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index bdcc172639e4..b842cd9a86f8 100644
@@ -1576,13 +1576,13 @@ static void _append_tdma(struct rtw89_dev *rtwdev)
 	if (ver->fcxtdma == 1) {
 		v = (struct rtw89_btc_fbtc_tdma *)&tlv->val[0];
 		tlv->len = sizeof(*v);
-		memcpy(v, &dm->tdma, sizeof(*v));
+		*v = dm->tdma;
 		btc->policy_len += BTC_TLV_HDR_LEN + sizeof(*v);
 	} else {
 		tlv->len = sizeof(*v3);
 		v3 = (struct rtw89_btc_fbtc_tdma_v3 *)&tlv->val[0];
 		v3->fver = ver->fcxtdma;
-		memcpy(&v3->tdma, &dm->tdma, sizeof(v3->tdma));
+		v3->tdma = dm->tdma;
 		btc->policy_len += BTC_TLV_HDR_LEN + sizeof(*v3);
 	}
 

2.34.1

wireless-next has taken my patch [1] that is identical to yours.

[1] https://lore.kernel.org/all/[email protected]/

Great!

I had mine ready on Oct 31, but I was waiting for the merge window to close before sending it.

Glad to see that the issue is fixed already. :)

Thanks
--
Gustavo

BTW we keep wireless-next open also during merge windows. So no need to hold up wireless patches because of the merge window. I know it's confusing that we do differently than how net-next works but this is easier for us, less patch build up.

https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches