Merge tag 'mac80211-for-davem-2015-04-01' of git://git.kernel.org/pub…

…/scm/linux/kernel/git/jberg/mac80211

Johannes Berg says:

====================
This contains just a single fix for a crash I happened to randomly
run into today during testing. It's clearly been around for a while,
but is pretty hard to trigger, even when I tried explicitly (and
modified the code to make it more likely) it rarely did.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

net/mac80211/agg-rx.c

@@ -49,8 +49,6 @@ static void ieee80211_free_tid_rx(struct rcu_head *h)
 		container_of(h, struct tid_ampdu_rx, rcu_head);
 	int i;
 
-	del_timer_sync(&tid_rx->reorder_timer);
-
 	for (i = 0; i < tid_rx->buf_size; i++)
 		__skb_queue_purge(&tid_rx->reorder_buf[i]);
 	kfree(tid_rx->reorder_buf);
@@ -93,6 +91,12 @@ void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
 
 	del_timer_sync(&tid_rx->session_timer);
 
+	/* make sure ieee80211_sta_reorder_release() doesn't re-arm the timer */
+	spin_lock_bh(&tid_rx->reorder_lock);
+	tid_rx->removed = true;
+	spin_unlock_bh(&tid_rx->reorder_lock);
+	del_timer_sync(&tid_rx->reorder_timer);
+
 	call_rcu(&tid_rx->rcu_head, ieee80211_free_tid_rx);
 }
 

net/mac80211/rx.c

@@ -873,9 +873,10 @@ static void ieee80211_sta_reorder_release(struct ieee80211_sub_if_data *sdata,
 
  set_release_timer:
 
-		mod_timer(&tid_agg_rx->reorder_timer,
-			  tid_agg_rx->reorder_time[j] + 1 +
-			  HT_RX_REORDER_BUF_TIMEOUT);
+		if (!tid_agg_rx->removed)
+			mod_timer(&tid_agg_rx->reorder_timer,
+				  tid_agg_rx->reorder_time[j] + 1 +
+				  HT_RX_REORDER_BUF_TIMEOUT);
 	} else {
 		del_timer(&tid_agg_rx->reorder_timer);
 	}

net/mac80211/sta_info.h

@@ -175,6 +175,7 @@ struct tid_ampdu_tx {
  * @reorder_lock: serializes access to reorder buffer, see below.
  * @auto_seq: used for offloaded BA sessions to automatically pick head_seq_and
  *	and ssn.
+ * @removed: this session is removed (but might have been found due to RCU)
  *
  * This structure's lifetime is managed by RCU, assignments to
  * the array holding it must hold the aggregation mutex.
@@ -199,6 +200,7 @@ struct tid_ampdu_rx {
 	u16 timeout;
 	u8 dialog_token;
 	bool auto_seq;
+	bool removed;
 };
 
 /**