This is a note to let you know that I've just added the patch titled
mac80211: prevent skb/txq mismatch
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: mac80211-prevent-skb-txq-mismatch.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Wed Dec 6 17:39:55 CET 2017
From: Michal Kazior michal.kazior@tieto.com Date: Fri, 13 Jan 2017 13:32:51 +0100 Subject: mac80211: prevent skb/txq mismatch
From: Michal Kazior michal.kazior@tieto.com
[ Upstream commit dbef53621116474bb883f76f0ba6b7640bc42332 ]
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] [<bf4252a4>] (ieee80211_tx_dequeue [mac80211]) from [<bf4b1388>] (ath10k_mac_tx_push_txq+0x54/0x1c0 [ath10k_core]) [<bf4b1388>] (ath10k_mac_tx_push_txq [ath10k_core]) from [<bf4bdfbc>] (ath10k_htt_txrx_compl_task+0xd78/0x11d0 [ath10k_core]) [<bf4bdfbc>] (ath10k_htt_txrx_compl_task [ath10k_core]) [<bf51c5a4>] (ath10k_pci_napi_poll+0x54/0xe8 [ath10k_pci]) [<bf51c5a4>] (ath10k_pci_napi_poll [ath10k_pci]) from [<c0572e90>] (net_rx_action+0xac/0x160)
Reported-by: Mohammed Shafi Shajakhan mohammed@qti.qualcomm.com Signed-off-by: Michal Kazior michal.kazior@tieto.com Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mac80211/tx.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)
--- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -1244,7 +1244,7 @@ ieee80211_tx_prepare(struct ieee80211_su
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; @@ -1258,10 +1258,13 @@ static struct txq_info *ieee80211_get_tx 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; } @@ -1499,23 +1502,17 @@ static bool ieee80211_queue_skb(struct i 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;
Patches currently in stable-queue which might be from michal.kazior@tieto.com are
queue-4.9/mac80211-prevent-skb-txq-mismatch.patch