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 <chunkeey@xxxxxxxxxxxxxx>
---
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 06ef5c1..0c19702 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2482,6 +2482,11 @@ 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);
@@ -2496,10 +2501,9 @@ 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);
}
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