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authorSumit Garg <sumit.garg@linaro.org>2020-04-07 13:10:55 +0300
committerJohannes Berg <johannes.berg@intel.com>2020-04-15 10:31:58 +0300
commit52e04b4ce5d03775b6a78f3ed1097480faacc9fd (patch)
tree52ed2229408e9a93884f3b6ade206abba0ef1428 /net
parenta710d21451ff2917b9004b65ba2f0db6380671d5 (diff)
downloadlinux-52e04b4ce5d03775b6a78f3ed1097480faacc9fd.tar.xz
mac80211: fix race in ieee80211_register_hw()
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@vger.kernel.org Signed-off-by: Sumit Garg <sumit.garg@linaro.org> Link: https://lore.kernel.org/r/1586254255-28713-1-git-send-email-sumit.garg@linaro.org [Johannes: fix rtnl imbalances] Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net')
-rw-r--r--net/mac80211/main.c24
1 files changed, 13 insertions, 11 deletions
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 8345926193de..0e9ad60fb2b3 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1069,7 +1069,7 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
local->hw.wiphy->signal_type = CFG80211_SIGNAL_TYPE_UNSPEC;
if (hw->max_signal <= 0) {
result = -EINVAL;
- goto fail_wiphy_register;
+ goto fail_workqueue;
}
}
@@ -1135,7 +1135,7 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
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;
@@ -1161,10 +1161,6 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
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.
@@ -1217,9 +1213,9 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
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");
@@ -1273,6 +1269,12 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
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)) {
@@ -1312,17 +1314,17 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
#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);
@@ -1372,8 +1374,8 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
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);
}