[PATCH] wifi: rtw89: coex: Annotate struct rtw89_btc_btf_set_slot_table with __counted_by

[Kees Cook]

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
rtw89_btc_btf_set_slot_table.

Cc: Ping-Ke Shih <pkshih@xxxxxxxxxxx>
Cc: Kalle Valo <kvalo@xxxxxxxxxx>
Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx>
Cc: linux-wireless@xxxxxxxxxxxxxxx
Cc: linux-hardening@xxxxxxxxxxxxxxx
Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1]
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 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 4ba8b3df70ae..d66a1152c3f5 100644
--- a/drivers/net/wireless/realtek/rtw89/coex.c
+++ b/drivers/net/wireless/realtek/rtw89/coex.c
@@ -237,7 +237,7 @@ struct rtw89_btc_btf_set_report {
 struct rtw89_btc_btf_set_slot_table {
 	u8 fver;
 	u8 tbl_num;
-	u8 buf[];
+	u8 buf[] __counted_by(tbl_num);
 } __packed;
 
 struct rtw89_btc_btf_set_mon_reg {
-- 
2.34.1