ath9k_htc: Fix bug in aggregation initiation

Accessing the sta pointer in TX completion without
approprate RCU protection is wrong. Fix this.

Also, RCU protection is needed when the station's
aggregation state is updated. Handle this properly.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/htc_drv_main.c

@@ -412,32 +412,31 @@ static int ath9k_htc_aggr_oper(struct ath9k_htc_priv *priv,
 	if (tid > ATH9K_HTC_MAX_TID)
 		return -EINVAL;
 
+	memset(&aggr, 0, sizeof(struct ath9k_htc_target_aggr));
+
 	rcu_read_lock();
+
+	/* Check if we are able to retrieve the station */
 	sta = ieee80211_find_sta(vif, sta_addr);
-	if (sta) {
-		ista = (struct ath9k_htc_sta *) sta->drv_priv;
-	} else {
+	if (!sta) {
 		rcu_read_unlock();
 		return -EINVAL;
 	}
 
-	if (!ista) {
-		rcu_read_unlock();
-		return -EINVAL;
-	}
+	ista = (struct ath9k_htc_sta *) sta->drv_priv;
 
-	memset(&aggr, 0, sizeof(struct ath9k_htc_target_aggr));
+	if (oper)
+		ista->tid_state[tid] = AGGR_START;
+	else
+		ista->tid_state[tid] = AGGR_STOP;
 
 	aggr.sta_index = ista->index;
+
 	rcu_read_unlock();
+
 	aggr.tidno = tid;
 	aggr.aggr_enable = oper;
 
-	if (oper)
-		ista->tid_state[tid] = AGGR_START;
-	else
-		ista->tid_state[tid] = AGGR_STOP;
-
 	WMI_CMD_BUF(WMI_TX_AGGR_ENABLE_CMDID, &aggr);
 	if (ret)
 		ath_print(common, ATH_DBG_CONFIG,

drivers/net/wireless/ath/ath9k/htc_drv_txrx.c

@@ -188,10 +188,20 @@ void ath9k_tx_tasklet(unsigned long data)
 		hdr = (struct ieee80211_hdr *) skb->data;
 		fc = hdr->frame_control;
 		tx_info = IEEE80211_SKB_CB(skb);
-		sta = tx_info->control.sta;
+
+		memset(&tx_info->status, 0, sizeof(tx_info->status));
 
 		rcu_read_lock();
 
+		sta = ieee80211_find_sta(priv->vif, hdr->addr1);
+		if (!sta) {
+			rcu_read_unlock();
+			ieee80211_tx_status(priv->hw, skb);
+			continue;
+		}
+
+		/* Check if we need to start aggregation */
+
 		if (sta && conf_is_ht(&priv->hw->conf) &&
 		    (priv->op_flags & OP_TXAGGR)
 		    && !(skb->protocol == cpu_to_be16(ETH_P_PAE))) {
@@ -213,7 +223,7 @@ void ath9k_tx_tasklet(unsigned long data)
 
 		rcu_read_unlock();
 
-		memset(&tx_info->status, 0, sizeof(tx_info->status));
+		/* Send status to mac80211 */
 		ieee80211_tx_status(priv->hw, skb);
 	}
 }