From dbef53621116474bb883f76f0ba6b7640bc42332 Mon Sep 17 00:00:00 2001 From: Michal Kazior Date: Fri, 13 Jan 2017 13:32:51 +0100 Subject: mac80211: prevent skb/txq mismatch Station structure is considered as not uploaded (to driver) until drv_sta_state() finishes. This call is however done after the structure is attached to mac80211 internal lists and hashes. This means mac80211 can lookup (and use) station structure before it is uploaded to a driver. If this happens (structure exists, but sta->uploaded is false) fast_tx path can still be taken. Deep in the fastpath call the sta->uploaded is checked against to derive "pubsta" argument for ieee80211_get_txq(). If sta->uploaded is false (and sta is actually non-NULL) ieee80211_get_txq() effectively downgraded to vif->txq. At first glance this may look innocent but coerces mac80211 into a state that is almost guaranteed (codel may drop offending skb) to crash because a station-oriented skb gets queued up on vif-oriented txq. The ieee80211_tx_dequeue() ends up looking at info->control.flags and tries to use txq->sta which in the fail case is NULL. It's probably pointless to pretend one can downgrade skb from sta-txq to vif-txq. Since downgrading unicast traffic to vif->txq must not be done there's no txq to put a frame on if sta->uploaded is false. Therefore the code is made to fall back to regular tx() op path if the described condition is hit. Only drivers using wake_tx_queue were affected. Example crash dump before fix: Unable to handle kernel paging request at virtual address ffffe26c PC is at ieee80211_tx_dequeue+0x204/0x690 [mac80211] [] (ieee80211_tx_dequeue [mac80211]) from [] (ath10k_mac_tx_push_txq+0x54/0x1c0 [ath10k_core]) [] (ath10k_mac_tx_push_txq [ath10k_core]) from [] (ath10k_htt_txrx_compl_task+0xd78/0x11d0 [ath10k_core]) [] (ath10k_htt_txrx_compl_task [ath10k_core]) [] (ath10k_pci_napi_poll+0x54/0xe8 [ath10k_pci]) [] (ath10k_pci_napi_poll [ath10k_pci]) from [] (net_rx_action+0xac/0x160) Reported-by: Mohammed Shafi Shajakhan Signed-off-by: Michal Kazior Signed-off-by: Johannes Berg --- net/mac80211/tx.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) (limited to 'net/mac80211') diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 0d8b716e509e..797e847cbc49 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -1243,7 +1243,7 @@ ieee80211_tx_prepare(struct ieee80211_sub_if_data *sdata, static struct txq_info *ieee80211_get_txq(struct ieee80211_local *local, struct ieee80211_vif *vif, - struct ieee80211_sta *pubsta, + struct sta_info *sta, struct sk_buff *skb) { struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; @@ -1257,10 +1257,13 @@ static struct txq_info *ieee80211_get_txq(struct ieee80211_local *local, if (!ieee80211_is_data(hdr->frame_control)) return NULL; - if (pubsta) { + if (sta) { u8 tid = skb->priority & IEEE80211_QOS_CTL_TID_MASK; - txq = pubsta->txq[tid]; + if (!sta->uploaded) + return NULL; + + txq = sta->sta.txq[tid]; } else if (vif) { txq = vif->txq; } @@ -1503,23 +1506,17 @@ static bool ieee80211_queue_skb(struct ieee80211_local *local, struct fq *fq = &local->fq; struct ieee80211_vif *vif; struct txq_info *txqi; - struct ieee80211_sta *pubsta; if (!local->ops->wake_tx_queue || sdata->vif.type == NL80211_IFTYPE_MONITOR) return false; - if (sta && sta->uploaded) - pubsta = &sta->sta; - else - pubsta = NULL; - if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) sdata = container_of(sdata->bss, struct ieee80211_sub_if_data, u.ap); vif = &sdata->vif; - txqi = ieee80211_get_txq(local, vif, pubsta, skb); + txqi = ieee80211_get_txq(local, vif, sta, skb); if (!txqi) return false; -- cgit v1.2.3