[PATCH v6 2/3] wifi: rtw88: skip already reset station in rtw_sta_remove()

[Kalpesh Solanki]

During firmware recovery, __fw_recovery_work() iterates over all
stations and invokes rtw_sta_remove() via rtw_reset_sta_iter().

If recovery is triggered concurrently with station teardown (such as
during ieee80211_set_disassoc() where mac80211 leaves LPS before
removing the AP station), rtw_ops_sta_remove() is subsequently called
for the same station. This causes rtw_sta_remove() to execute twice,
leading to a double free of si->mask and an underflow of rtwdev->sta_cnt.

Cancel pending rate control work first, as rtw_ops_sta_rc_update() can
still schedule rc_work after the station was reset. Then check si->vif
and return early if the station was already reset. Clear si->vif,
si->mask, and si->use_cfg_mask upon removal to ensure clean teardown
and avoid a NULL pointer dereference in rtw_rate_mask_cfg() if mac80211
re-adds the station across recovery restart.

Fixes: 5c831644e1f4 ("rtw88: handle and recover when firmware crash")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Kalpesh Solanki <skalpesh942@xxxxxxxxx>
---
 drivers/net/wireless/realtek/rtw88/main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtw88/main.c b/drivers/net/wireless/realtek/rtw88/main.c
index f7708ad17b6..8e62d38a269 100644
--- a/drivers/net/wireless/realtek/rtw88/main.c
+++ b/drivers/net/wireless/realtek/rtw88/main.c
@@ -386,6 +386,9 @@ void rtw_sta_remove(struct rtw_dev *rtwdev, struct ieee80211_sta *sta,
 
 	cancel_work_sync(&si->rc_work);
 
+	if (!vif)
+		return;
+
 	if (vif->type != NL80211_IFTYPE_STATION || sta->tdls)
 		rtw_release_macid(rtwdev, si->mac_id);
 	if (fw_exist)
@@ -395,8 +398,11 @@ void rtw_sta_remove(struct rtw_dev *rtwdev, struct ieee80211_sta *sta,
 		rtw_txq_cleanup(rtwdev, sta->txq[i]);
 
 	kfree(si->mask);
+	si->mask = NULL;
+	si->use_cfg_mask = false;
 
 	rtwdev->sta_cnt--;
+	si->vif = NULL;
 	rtw_dbg(rtwdev, RTW_DBG_STATE, "sta %pM with macid %d left\n",
 		sta->addr, si->mac_id);
 }
-- 
2.53.0