mt76: mt7615: check sta_rates pointer in mt7615_sta_rate_tbl_update

Check sta_rates pointer value in mt7615_sta_rate_tbl_update routine
since minstrel_ht_update_rates can fail allocating rates array.

Fixes: 04b8e659 ("mt76: add mac80211 driver for MT7615 PCIe-based chipsets")
Signed-off-by: NLorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: NFelix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7615/main.c

@@ -689,6 +689,9 @@ static void mt7615_sta_rate_tbl_update(struct ieee80211_hw *hw,
 	struct ieee80211_sta_rates *sta_rates = rcu_dereference(sta->rates);
 	int i;
 
+	if (!sta_rates)
+		return;
+
 	spin_lock_bh(&dev->mt76.lock);
 	for (i = 0; i < ARRAY_SIZE(msta->rates); i++) {
 		msta->rates[i].idx = sta_rates->rate[i].idx;