From: Sumit Garg sumit.garg@linaro.org
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@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@linar... [Johannes: fix rtnl imbalances] Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/mac80211/main.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-)
--- a/net/mac80211/main.c +++ b/net/mac80211/main.c @@ -1045,7 +1045,7 @@ 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; } }
@@ -1107,7 +1107,7 @@ 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; @@ -1133,10 +1133,6 @@ 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. @@ -1192,9 +1188,9 @@ 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"); @@ -1248,6 +1244,12 @@ 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)) { @@ -1287,17 +1289,17 @@ 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); @@ -1347,8 +1349,8 @@ 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); }