mac80211: handle station TX latency allocation errors

When the station's TX latency data structures need to be
allocated, handle failures properly and also free all the
structures if there are any other problems.

Move the allocation code up so that allocation failures
don't trigger rate control algorithm calls.
Reported-by: ZHAO Gang <gamerh2o@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/sta_info.c

@@ -300,6 +300,35 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
 	if (!sta)
 		return NULL;
 
+	rcu_read_lock();
+	tx_latency = rcu_dereference(local->tx_latency);
+	/* init stations Tx latency statistics && TID bins */
+	if (tx_latency) {
+		sta->tx_lat = kzalloc(IEEE80211_NUM_TIDS *
+				      sizeof(struct ieee80211_tx_latency_stat),
+				      GFP_ATOMIC);
+		if (!sta->tx_lat) {
+			rcu_read_unlock();
+			goto free;
+		}
+
+		if (tx_latency->n_ranges) {
+			for (i = 0; i < IEEE80211_NUM_TIDS; i++) {
+				/* size of bins is size of the ranges +1 */
+				sta->tx_lat[i].bin_count =
+					tx_latency->n_ranges + 1;
+				sta->tx_lat[i].bins =
+					kcalloc(sta->tx_lat[i].bin_count,
+						sizeof(u32), GFP_ATOMIC);
+				if (!sta->tx_lat[i].bins) {
+					rcu_read_unlock();
+					goto free;
+				}
+			}
+		}
+	}
+	rcu_read_unlock();
+
 	spin_lock_init(&sta->lock);
 	INIT_WORK(&sta->drv_unblock_wk, sta_unblock);
 	INIT_WORK(&sta->ampdu_mlme.work, ieee80211_ba_session_work);
@@ -324,10 +353,8 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
 	for (i = 0; i < ARRAY_SIZE(sta->chain_signal_avg); i++)
 		ewma_init(&sta->chain_signal_avg[i], 1024, 8);
 
-	if (sta_prepare_rate_control(local, sta, gfp)) {
-		kfree(sta);
-		return NULL;
-	}
+	if (sta_prepare_rate_control(local, sta, gfp))
+		goto free;
 
 	for (i = 0; i < IEEE80211_NUM_TIDS; i++) {
 		/*
@@ -371,34 +398,17 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
 		}
 	}
 
-	rcu_read_lock();
-
-	tx_latency = rcu_dereference(local->tx_latency);
-	/* init stations Tx latency statistics && TID bins */
-	if (tx_latency)
-		sta->tx_lat = kzalloc(IEEE80211_NUM_TIDS *
-				      sizeof(struct ieee80211_tx_latency_stat),
-				      GFP_ATOMIC);
-
-	/*
-	 * if Tx latency and bins are enabled and the previous allocation
-	 * succeeded
-	 */
-	if (tx_latency && tx_latency->n_ranges && sta->tx_lat)
-		for (i = 0; i < IEEE80211_NUM_TIDS; i++) {
-			/* size of bins is size of the ranges +1 */
-			sta->tx_lat[i].bin_count =
-				tx_latency->n_ranges + 1;
-			sta->tx_lat[i].bins  = kcalloc(sta->tx_lat[i].bin_count,
-						       sizeof(u32),
-						       GFP_ATOMIC);
-		}
-
-	rcu_read_unlock();
-
 	sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr);
-
 	return sta;
+
+free:
+	if (sta->tx_lat) {
+		for (i = 0; i < IEEE80211_NUM_TIDS; i++)
+			kfree(sta->tx_lat[i].bins);
+		kfree(sta->tx_lat);
+	}
+	kfree(sta);
+	return NULL;
 }
 
 static int sta_info_insert_check(struct sta_info *sta)