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108 lines
3.5 KiB
Diff
108 lines
3.5 KiB
Diff
From: Michal Kazior <michal.kazior@tieto.com>
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Date: Fri, 13 Jan 2017 13:32:51 +0100
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Subject: [PATCH] mac80211: prevent skb/txq mismatch
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Station structure is considered as not uploaded
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(to driver) until drv_sta_state() finishes. This
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call is however done after the structure is
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attached to mac80211 internal lists and hashes.
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This means mac80211 can lookup (and use) station
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structure before it is uploaded to a driver.
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If this happens (structure exists, but
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sta->uploaded is false) fast_tx path can still be
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taken. Deep in the fastpath call the sta->uploaded
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is checked against to derive "pubsta" argument for
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ieee80211_get_txq(). If sta->uploaded is false
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(and sta is actually non-NULL) ieee80211_get_txq()
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effectively downgraded to vif->txq.
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At first glance this may look innocent but coerces
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mac80211 into a state that is almost guaranteed
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(codel may drop offending skb) to crash because a
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station-oriented skb gets queued up on
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vif-oriented txq. The ieee80211_tx_dequeue() ends
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up looking at info->control.flags and tries to use
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txq->sta which in the fail case is NULL.
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It's probably pointless to pretend one can
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downgrade skb from sta-txq to vif-txq.
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Since downgrading unicast traffic to vif->txq must
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not be done there's no txq to put a frame on if
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sta->uploaded is false. Therefore the code is made
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to fall back to regular tx() op path if the
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described condition is hit.
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Only drivers using wake_tx_queue were affected.
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Example crash dump before fix:
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Unable to handle kernel paging request at virtual address ffffe26c
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PC is at ieee80211_tx_dequeue+0x204/0x690 [mac80211]
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[<bf4252a4>] (ieee80211_tx_dequeue [mac80211]) from
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[<bf4b1388>] (ath10k_mac_tx_push_txq+0x54/0x1c0 [ath10k_core])
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[<bf4b1388>] (ath10k_mac_tx_push_txq [ath10k_core]) from
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[<bf4bdfbc>] (ath10k_htt_txrx_compl_task+0xd78/0x11d0 [ath10k_core])
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[<bf4bdfbc>] (ath10k_htt_txrx_compl_task [ath10k_core])
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[<bf51c5a4>] (ath10k_pci_napi_poll+0x54/0xe8 [ath10k_pci])
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[<bf51c5a4>] (ath10k_pci_napi_poll [ath10k_pci]) from
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[<c0572e90>] (net_rx_action+0xac/0x160)
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Reported-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
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Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
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---
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--- a/net/mac80211/tx.c
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+++ b/net/mac80211/tx.c
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@@ -798,7 +798,7 @@ static __le16 ieee80211_tx_next_seq(stru
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static struct txq_info *ieee80211_get_txq(struct ieee80211_local *local,
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struct ieee80211_vif *vif,
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- struct ieee80211_sta *pubsta,
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+ struct sta_info *sta,
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struct sk_buff *skb)
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{
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struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
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@@ -812,10 +812,13 @@ static struct txq_info *ieee80211_get_tx
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if (!ieee80211_is_data(hdr->frame_control))
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return NULL;
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- if (pubsta) {
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+ if (sta) {
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u8 tid = skb->priority & IEEE80211_QOS_CTL_TID_MASK;
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- txq = pubsta->txq[tid];
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+ if (!sta->uploaded)
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+ return NULL;
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+
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+ txq = sta->sta.txq[tid];
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} else if (vif) {
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txq = vif->txq;
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}
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@@ -1503,23 +1506,17 @@ static bool ieee80211_queue_skb(struct i
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struct fq *fq = &local->fq;
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struct ieee80211_vif *vif;
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struct txq_info *txqi;
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- struct ieee80211_sta *pubsta;
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if (!local->ops->wake_tx_queue ||
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sdata->vif.type == NL80211_IFTYPE_MONITOR)
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return false;
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- if (sta && sta->uploaded)
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- pubsta = &sta->sta;
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- else
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- pubsta = NULL;
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-
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if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
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sdata = container_of(sdata->bss,
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struct ieee80211_sub_if_data, u.ap);
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vif = &sdata->vif;
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- txqi = ieee80211_get_txq(local, vif, pubsta, skb);
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+ txqi = ieee80211_get_txq(local, vif, sta, skb);
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if (!txqi)
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return false;
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