kernel_optimize_test/net/mac80211
Michal Kazior dbef536211 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>
2017-01-13 14:47:21 +01:00
..
aes_ccm.c
aes_ccm.h
aes_cmac.c
aes_cmac.h
aes_gcm.c
aes_gcm.h
aes_gmac.c
aes_gmac.h
agg-rx.c
agg-tx.c
cfg.c
chan.c mac80211: calculate min channel width correctly 2017-01-11 16:34:51 +01:00
debug.h
debugfs_key.c
debugfs_key.h
debugfs_netdev.c
debugfs_netdev.h
debugfs_sta.c
debugfs_sta.h
debugfs.c
debugfs.h
driver-ops.c
driver-ops.h
ethtool.c
fils_aead.c
fils_aead.h
ht.c
ibss.c
ieee80211_i.h linux: drop __bitwise__ everywhere 2016-12-16 00:13:41 +02:00
iface.c mac80211: recalculate min channel width on VHT opmode changes 2017-01-11 16:35:05 +01:00
Kconfig
key.c mac80211: don't call drv_set_default_unicast_key() for VLANs 2016-12-13 15:57:59 +01:00
key.h
led.c
led.h
main.c mac80211: initialize SMPS field in HT capabilities 2017-01-13 11:31:26 +01:00
Makefile Makefile: drop -D__CHECK_ENDIAN__ from cflags 2016-12-16 00:13:43 +02:00
mesh_hwmp.c
mesh_pathtbl.c
mesh_plink.c
mesh_ps.c
mesh_sync.c
mesh.c
mesh.h
michael.c
michael.h
mlme.c
ocb.c
offchannel.c
pm.c
rate.c mac80211: calculate min channel width correctly 2017-01-11 16:34:51 +01:00
rate.h
rc80211_minstrel_debugfs.c
rc80211_minstrel_ht_debugfs.c
rc80211_minstrel_ht.c
rc80211_minstrel_ht.h
rc80211_minstrel.c
rc80211_minstrel.h
rx.c mac80211: recalculate min channel width on VHT opmode changes 2017-01-11 16:35:05 +01:00
scan.c
spectmgmt.c
sta_info.c mac80211: fix the TID on NDPs sent as EOSP carrier 2017-01-11 16:32:58 +01:00
sta_info.h
status.c
tdls.c
tkip.c
tkip.h
trace_msg.h
trace.c
trace.h
tx.c mac80211: prevent skb/txq mismatch 2017-01-13 14:47:21 +01:00
util.c
vht.c mac80211: recalculate min channel width on VHT opmode changes 2017-01-11 16:35:05 +01:00
wep.c
wep.h
wme.c
wme.h
wpa.c
wpa.h