From 2c15a0cf27a74213a714cc7be31685b841f7c1ac Mon Sep 17 00:00:00 2001 From: Christian Lamparter Date: Tue, 24 Aug 2010 19:22:42 +0200 Subject: mac80211: fix rcu-unsafe pointer dereference This patch fixes a potential crash (null-pointer de- reference) which was introduced in my previous patch: "mac80211: AMPDU rx reorder timeout timer" During a BA teardown, the pointer to the soon-to-be-gone tid_ampdu_rx element will be nullified. Therefore the release timer mechanism has to be careful not to accidentally access the item without any RCU protection. Signed-off-by: Christian Lamparter Signed-off-by: John W. Linville --- net/mac80211/rx.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'net/mac80211') diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index e1844f7085de..e67deb48af5c 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -2479,6 +2479,11 @@ void ieee80211_release_reorder_timeout(struct sta_info *sta, int tid) { struct sk_buff_head frames; struct ieee80211_rx_data rx = { }; + struct tid_ampdu_rx *tid_agg_rx; + + tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]); + if (!tid_agg_rx) + return; __skb_queue_head_init(&frames); @@ -2493,10 +2498,9 @@ void ieee80211_release_reorder_timeout(struct sta_info *sta, int tid) test_bit(SCAN_OFF_CHANNEL, &sta->local->scanning))) rx.flags |= IEEE80211_RX_IN_SCAN; - spin_lock(&sta->ampdu_mlme.tid_rx[tid]->reorder_lock); - ieee80211_sta_reorder_release(&sta->local->hw, - sta->ampdu_mlme.tid_rx[tid], &frames); - spin_unlock(&sta->ampdu_mlme.tid_rx[tid]->reorder_lock); + spin_lock(&tid_agg_rx->reorder_lock); + ieee80211_sta_reorder_release(&sta->local->hw, tid_agg_rx, &frames); + spin_unlock(&tid_agg_rx->reorder_lock); ieee80211_rx_handlers(&rx, &frames); } -- cgit v1.2.3-59-g8ed1b