mt76: mt7603: check sta_rates pointer in mt7603_sta_rate_tbl_update

Check sta_rates pointer value in mt7603_sta_rate_tbl_update routine
since minstrel_ht_update_rates can fail allocating rates array.

Fixes: c8846e10 ("mt76: add driver for MT7603E and MT7628/7688")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7603/main.c

@@ -641,6 +641,9 @@ mt7603_sta_rate_tbl_update(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	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;