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mac80211: fix possible tid_rx->reorder_timer use after free 

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>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Stanislaw Gruszka 2012-03-19 16:00:26 +01:00 committed by John W. Linville
parent 4e808a38fd
commit d72308bff5
1 changed files with 2 additions and 1 deletions
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3
net/mac80211/agg-rx.c
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@ -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);
}