[ 003/171] mac80211: sync acccess to tx_filtered/ps_tx_buf queues

[Greg Kroah-Hartman]

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

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

From: Arik Nemtsov <arik@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Ido Yariv <ido@xxxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/mac80211/sta_info.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -959,6 +959,7 @@ void ieee80211_sta_ps_deliver_wakeup(str
 	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(str
 	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;
 	}


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