[PATCH 077/241] mac80211: sync acccess to tx_filtered/ps_tx_buf queues

[Herton Ronaldo Krzesinski]

3.5.7.2 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arik Nemtsov <arik at wizery.com>

commit 987c285c2ae2e4e32aca3a9b3252d28171c75711 upstream.

These are accessed without a lock when ending STA PSM. If the
sta_cleanup timer accesses these lists at the same time, we might crash.

This may fix some mysterious crashes we had during
ieee80211_sta_ps_deliver_wakeup.

Signed-off-by: Arik Nemtsov <arik at wizery.com>
Signed-off-by: Ido Yariv <ido at wizery.com>
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 net/mac80211/sta_info.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 277bd96..343484c 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -959,6 +959,7 @@ void ieee80211_sta_ps_deliver_wakeup(struct sta_info *sta)
 	struct ieee80211_local *local = sdata->local;
 	struct sk_buff_head pending;
 	int filtered = 0, buffered = 0, ac;
+	unsigned long flags;
 
 	clear_sta_flag(sta, WLAN_STA_SP);
 
@@ -974,12 +975,16 @@ void ieee80211_sta_ps_deliver_wakeup(struct sta_info *sta)
 	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
 		int count = skb_queue_len(&pending), tmp;
 
+		spin_lock_irqsave(&sta->tx_filtered[ac].lock, flags);
 		skb_queue_splice_tail_init(&sta->tx_filtered[ac], &pending);
+		spin_unlock_irqrestore(&sta->tx_filtered[ac].lock, flags);
 		tmp = skb_queue_len(&pending);
 		filtered += tmp - count;
 		count = tmp;
 
+		spin_lock_irqsave(&sta->ps_tx_buf[ac].lock, flags);
 		skb_queue_splice_tail_init(&sta->ps_tx_buf[ac], &pending);
+		spin_unlock_irqrestore(&sta->ps_tx_buf[ac].lock, flags);
 		tmp = skb_queue_len(&pending);
 		buffered += tmp - count;
 	}
-- 
1.7.9.5