wifi: rtw89: add bounds check on firmware mac_id in link lookup

[ Upstream commit 6d88244 ]

The mac_id field in RX descriptors is 8 bits wide (0-255), but
assoc_link_on_macid[] has only RTW89_MAX_MAC_ID_NUM (128) entries.
While the driver currently assigns mac_id values below 128, the
descriptor value comes from firmware and is not validated before use
as an array index. Add a defensive bounds check in
rtw89_assoc_link_rcu_dereference() to guard against out-of-range
firmware values.

Fixes: 144c6cd ("wifi: rtw89: 8922a: configure AP_LINK_PS if FW supports")
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20260421111442.3395411-1-tristmd@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Tristan Madani

drivers/net/wireless/realtek/rtw89/core.h

@@ -6254,6 +6254,9 @@ static inline void rtw89_assoc_link_clr(struct rtw89_sta_link *rtwsta_link)
 static inline struct rtw89_sta_link *
 rtw89_assoc_link_rcu_dereference(struct rtw89_dev *rtwdev, u8 macid)
 {
+	if (unlikely(macid >= RTW89_MAX_MAC_ID_NUM))
+		return NULL;
+
 	return rcu_dereference(rtwdev->assoc_link_on_macid[macid]);
 }