2009-01-27 08:04:11

by Sujith

[permalink] [raw]
Subject: [PATCH] ath9k: Fix station access in aggregation completion

The ieee80211_sta pointer in the SKB's TX control info
area is not guaranteed to be valid after returning from the tx() callback.
Use ieee80211_find_sta() instead and return early if the station
is no longer present.

Signed-off-by: Sujith <[email protected]>
---
drivers/net/wireless/ath9k/xmit.c | 20 +++++++++++++++-----
1 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/ath9k/xmit.c b/drivers/net/wireless/ath9k/xmit.c
index 1b83673..007ca91 100644
--- a/drivers/net/wireless/ath9k/xmit.c
+++ b/drivers/net/wireless/ath9k/xmit.c
@@ -268,7 +268,8 @@ static void ath_tx_complete_aggr(struct ath_softc *sc, struct ath_txq *txq,
{
struct ath_node *an = NULL;
struct sk_buff *skb;
- struct ieee80211_tx_info *tx_info;
+ struct ieee80211_sta *sta;
+ struct ieee80211_hdr *hdr;
struct ath_atx_tid *tid = NULL;
struct ath_buf *bf_next, *bf_last = bf->bf_lastbf;
struct ath_desc *ds = bf_last->bf_desc;
@@ -278,13 +279,19 @@ static void ath_tx_complete_aggr(struct ath_softc *sc, struct ath_txq *txq,
int isaggr, txfail, txpending, sendbar = 0, needreset = 0;

skb = (struct sk_buff *)bf->bf_mpdu;
- tx_info = IEEE80211_SKB_CB(skb);
+ hdr = (struct ieee80211_hdr *)skb->data;

- if (tx_info->control.sta) {
- an = (struct ath_node *)tx_info->control.sta->drv_priv;
- tid = ATH_AN_2_TID(an, bf->bf_tidno);
+ rcu_read_lock();
+
+ sta = ieee80211_find_sta(sc->hw, hdr->addr1);
+ if (!sta) {
+ rcu_read_unlock();
+ return;
}

+ an = (struct ath_node *)sta->drv_priv;
+ tid = ATH_AN_2_TID(an, bf->bf_tidno);
+
isaggr = bf_isaggr(bf);
memset(ba, 0, WME_BA_BMP_SIZE >> 3);

@@ -391,6 +398,7 @@ static void ath_tx_complete_aggr(struct ath_softc *sc, struct ath_txq *txq,
/* send buffered frames as singles */
ath_tx_flush_tid(sc, tid);
}
+ rcu_read_unlock();
return;
}

@@ -402,6 +410,8 @@ static void ath_tx_complete_aggr(struct ath_softc *sc, struct ath_txq *txq,
spin_unlock_bh(&txq->axq_lock);
}

+ rcu_read_unlock();
+
if (needreset)
ath_reset(sc, false);
}
--
1.6.1