From: Sumit Garg <sumit.garg@xxxxxxxxxx>
commit 52e04b4ce5d03775b6a78f3ed1097480faacc9fd upstream.
A race condition leading to a kernel crash is observed during invocation
of ieee80211_register_hw() on a dragonboard410c device having wcn36xx
driver built as a loadable module along with a wifi manager in user-space
waiting for a wifi device (wlanX) to be active.
Sequence diagram for a particular kernel crash scenario:
user-space ieee80211_register_hw() ieee80211_tasklet_handler()
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
| | |
|<---phy0----wiphy_register() |
|-----iwd if_add---->| |
| |<---IRQ----(RX packet)
| Kernel crash |
| due to unallocated |
| workqueue. |
| | |
| alloc_ordered_workqueue() |
| | |
| Misc wiphy init. |
| | |
| ieee80211_if_add() |
| | |
As evident from above sequence diagram, this race condition isn't specific
to a particular wifi driver but rather the initialization sequence in
ieee80211_register_hw() needs to be fixed. So re-order the initialization
sequence and the updated sequence diagram would look like:
user-space ieee80211_register_hw() ieee80211_tasklet_handler()
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
| | |
| alloc_ordered_workqueue() |
| | |
| Misc wiphy init. |
| | |
|<---phy0----wiphy_register() |
|-----iwd if_add---->| |
| |<---IRQ----(RX packet)
| | |
| ieee80211_if_add() |
| | |
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
Link: https://lore.kernel.org/r/1586254255-28713-1-git-send-email-sumit.garg@xxxxxxxxxx
[Johannes: fix rtnl imbalances]
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/mac80211/main.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1051,7 +1051,7 @@ int ieee80211_register_hw(struct ieee802
local->hw.wiphy->signal_type = CFG80211_SIGNAL_TYPE_UNSPEC;
if (hw->max_signal <= 0) {
result = -EINVAL;
- goto fail_wiphy_register;
+ goto fail_workqueue;
}
}
@@ -1113,7 +1113,7 @@ int ieee80211_register_hw(struct ieee802
result = ieee80211_init_cipher_suites(local);
if (result < 0)
- goto fail_wiphy_register;
+ goto fail_workqueue;
if (!local->ops->remain_on_channel)
local->hw.wiphy->max_remain_on_channel_duration = 5000;
@@ -1139,10 +1139,6 @@ int ieee80211_register_hw(struct ieee802
local->hw.wiphy->max_num_csa_counters = IEEE80211_MAX_CSA_COUNTERS_NUM;
- result = wiphy_register(local->hw.wiphy);
- if (result < 0)
- goto fail_wiphy_register;
-
/*
* We use the number of queues for feature tests (QoS, HT) internally
* so restrict them appropriately.
@@ -1198,9 +1194,9 @@ int ieee80211_register_hw(struct ieee802
goto fail_flows;
rtnl_lock();
-
result = ieee80211_init_rate_ctrl_alg(local,
hw->rate_control_algorithm);
+ rtnl_unlock();
if (result < 0) {
wiphy_debug(local->hw.wiphy,
"Failed to initialize rate control algorithm\n");
@@ -1254,6 +1250,12 @@ int ieee80211_register_hw(struct ieee802
local->sband_allocated |= BIT(band);
}
+ result = wiphy_register(local->hw.wiphy);
+ if (result < 0)
+ goto fail_wiphy_register;
+
+ rtnl_lock();
+
/* add one default STA interface if supported */
if (local->hw.wiphy->interface_modes & BIT(NL80211_IFTYPE_STATION) &&
!ieee80211_hw_check(hw, NO_AUTO_VIF)) {
@@ -1293,17 +1295,17 @@ int ieee80211_register_hw(struct ieee802
#if defined(CONFIG_INET) || defined(CONFIG_IPV6)
fail_ifa:
#endif
+ wiphy_unregister(local->hw.wiphy);
+ fail_wiphy_register:
rtnl_lock();
rate_control_deinitialize(local);
ieee80211_remove_interfaces(local);
- fail_rate:
rtnl_unlock();
+ fail_rate:
fail_flows:
ieee80211_led_exit(local);
destroy_workqueue(local->workqueue);
fail_workqueue:
- wiphy_unregister(local->hw.wiphy);
- fail_wiphy_register:
if (local->wiphy_ciphers_allocated)
kfree(local->hw.wiphy->cipher_suites);
kfree(local->int_scan_req);
@@ -1353,8 +1355,8 @@ void ieee80211_unregister_hw(struct ieee
skb_queue_purge(&local->skb_queue_unreliable);
skb_queue_purge(&local->skb_queue_tdls_chsw);
- destroy_workqueue(local->workqueue);
wiphy_unregister(local->hw.wiphy);
+ destroy_workqueue(local->workqueue);
ieee80211_led_exit(local);
kfree(local->int_scan_req);
}
