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| author | Michal Kazior <michal.kazior@tieto.com> | 2017-01-13 13:32:51 +0100 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2017-01-13 14:47:21 +0100 |
| commit | dbef53621116474bb883f76f0ba6b7640bc42332 (patch) | |
| tree | bf146f634cdb9db11cd5e692512fe08e248a0a98 /net/sched/act_skbedit.c | |
| parent | 43071d8fb3b7f589d72663c496a6880fb097533c (diff) | |
| download | linux-dbef53621116474bb883f76f0ba6b7640bc42332.tar.bz2 | |
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]
[<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>
Diffstat (limited to 'net/sched/act_skbedit.c')
0 files changed, 0 insertions, 0 deletions