From 827d42c9ac91ddd728e4f4a31fefb906ef2ceff7 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Sun, 22 Nov 2009 12:28:41 +0100 Subject: mac80211: fix spurious delBA handling Lennert Buytenhek noticed that delBA handling in mac80211 was broken and has remotely triggerable problems, some of which are due to some code shuffling I did that ended up changing the order in which things were done -- this was commit d75636ef9c1af224f1097941879d5a8db7cd04e5 Author: Johannes Berg Date: Tue Feb 10 21:25:53 2009 +0100 mac80211: RX aggregation: clean up stop session and other parts were already present in the original commit d92684e66091c0f0101819619b315b4bb8b5bcc5 Author: Ron Rindjunsky Date: Mon Jan 28 14:07:22 2008 +0200 mac80211: A-MPDU Tx add delBA from recipient support The first problem is that I moved a BUG_ON before various checks -- thereby making it possible to hit. As the comment indicates, the BUG_ON can be removed since the ampdu_action callback must already exist when the state is != IDLE. The second problem isn't easily exploitable but there's a race condition due to unconditionally setting the state to OPERATIONAL when a delBA frame is received, even when no aggregation session was ever initiated. All the drivers accept stopping the session even then, but that opens a race window where crashes could happen before the driver accepts it. Right now, a WARN_ON may happen with non-HT drivers, while the race opens only for HT drivers. For this case, there are two things necessary to fix it: 1) don't process spurious delBA frames, and be more careful about the session state; don't drop the lock 2) HT drivers need to be prepared to handle a session stop even before the session was really started -- this is true for all drivers (that support aggregation) but iwlwifi which can be fixed easily. The other HT drivers (ath9k and ar9170) are behaving properly already. Reported-by: Lennert Buytenhek Cc: stable@kernel.org Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- net/mac80211/ht.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'net/mac80211/ht.c') diff --git a/net/mac80211/ht.c b/net/mac80211/ht.c index 48ef1a282b9..cdc58e61d92 100644 --- a/net/mac80211/ht.c +++ b/net/mac80211/ht.c @@ -141,7 +141,6 @@ void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata, struct sta_info *sta, struct ieee80211_mgmt *mgmt, size_t len) { - struct ieee80211_local *local = sdata->local; u16 tid, params; u16 initiator; @@ -161,10 +160,9 @@ void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata, WLAN_BACK_INITIATOR, 0); else { /* WLAN_BACK_RECIPIENT */ spin_lock_bh(&sta->lock); - sta->ampdu_mlme.tid_state_tx[tid] = - HT_AGG_STATE_OPERATIONAL; + if (sta->ampdu_mlme.tid_state_tx[tid] & HT_ADDBA_REQUESTED_MSK) + ___ieee80211_stop_tx_ba_session(sta, tid, + WLAN_BACK_RECIPIENT); spin_unlock_bh(&sta->lock); - ieee80211_stop_tx_ba_session(&local->hw, sta->sta.addr, tid, - WLAN_BACK_RECIPIENT); } } -- cgit v1.2.3