mac80211: fix possible tid_rx->reorder_timer use after free

  from Stanislaw Gruska (rhbz 804007)

1 files changed, 42 insertions, 0 deletions

diff --git a/mac80211-fix-possible-tid_rx-reorder_timer-use-after-free.patch b/mac80211-fix-possible-tid_rx-reorder_timer-use-after-free.patch
new file mode 100644
index 000000000..accda8afc
--- /dev/null
+++ b/mac80211-fix-possible-tid_rx-reorder_timer-use-after-free.patch
@@ -0,0 +1,42 @@
+Is possible that we will arm the tid_rx->reorder_timer after
+del_timer_sync() in ___ieee80211_stop_rx_ba_session(). We need to stop
+timer after RCU grace period finish, so move it to
+ieee80211_free_tid_rx(). Timer will not be armed again, as
+rcu_dereference(sta->ampdu_mlme.tid_rx[tid]) will return NULL.
+
+Debug object detected problem with the following warning:
+ODEBUG: free active (active state 0) object type: timer_list hint: sta_rx_agg_reorder_timer_expired+0x0/0xf0 [mac80211]
+
+Bug report (with all warning messages):
+https://bugzilla.redhat.com/show_bug.cgi?id=804007
+
+Reported-by: "jan p. springer" <jsd@igroup.org>
+Cc: stable@vger.kernel.org
+Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
+---
+ net/mac80211/agg-rx.c |    3 ++-
+ 1 files changed, 2 insertions(+), 1 deletions(-)
+
+diff --git a/net/mac80211/agg-rx.c b/net/mac80211/agg-rx.c
+index 1068f66..64d3ce5 100644
+--- a/net/mac80211/agg-rx.c
++++ b/net/mac80211/agg-rx.c
+@@ -49,6 +49,8 @@ static void ieee80211_free_tid_rx(struct rcu_head *h)
+ 		container_of(h, struct tid_ampdu_rx, rcu_head);
+ 	int i;
+ 
++	del_timer_sync(&tid_rx->reorder_timer);
++
+ 	for (i = 0; i < tid_rx->buf_size; i++)
+ 		dev_kfree_skb(tid_rx->reorder_buf[i]);
+ 	kfree(tid_rx->reorder_buf);
+@@ -91,7 +93,6 @@ void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
+ 				     tid, WLAN_BACK_RECIPIENT, reason);
+ 
+ 	del_timer_sync(&tid_rx->session_timer);
+-	del_timer_sync(&tid_rx->reorder_timer);
+ 
+ 	call_rcu(&tid_rx->rcu_head, ieee80211_free_tid_rx);
+ }
+-- 
+1.7.1