netdev - [PATCH AUTOSEL 4.19 65/97] mac80211: fix a kernel panic when TXing after TXQ teardown

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Date:   Wed, 26 Dec 2018 17:35:25 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Sara Sharon <sara.sharon@...el.com>,
        Luca Coelho <luciano.coelho@...el.com>,
        Johannes Berg <johannes.berg@...el.com>,
        Sasha Levin <sashal@...nel.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 65/97] mac80211: fix a kernel panic when TXing after TXQ teardown

From: Sara Sharon <sara.sharon@...el.com>

[ Upstream commit a50e5fb8db83c5b57392204c21ea6c5c4ccefde6 ]

Recently TXQ teardown was moved earlier in ieee80211_unregister_hw(),
to avoid a use-after-free of the netdev data. However, interfaces
aren't fully removed at the point, and cfg80211_shutdown_all_interfaces
can for example, TX a deauth frame. Move the TXQ teardown to the
point between cfg80211_shutdown_all_interfaces and the free of
netdev queues, so we can be sure they are torn down before netdev
is freed, but after there is no ongoing TX.

Fixes: 77cfaf52eca5 ("mac80211: Run TXQ teardown code before de-registering interfaces")
Signed-off-by: Sara Sharon <sara.sharon@...el.com>
Signed-off-by: Luca Coelho <luciano.coelho@...el.com>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/mac80211/iface.c | 3 +++
 net/mac80211/main.c  | 2 --
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 5f3c81e705c7..3a0171a65db3 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -7,6 +7,7 @@
  * Copyright 2008, Johannes Berg <johannes@...solutions.net>
  * Copyright 2013-2014  Intel Mobile Communications GmbH
  * Copyright (c) 2016        Intel Deutschland GmbH
+ * Copyright (C) 2018 Intel Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -1951,6 +1952,8 @@ void ieee80211_remove_interfaces(struct ieee80211_local *local)
 	WARN(local->open_count, "%s: open count remains %d\n",
 	     wiphy_name(local->hw.wiphy), local->open_count);
 
+	ieee80211_txq_teardown_flows(local);
+
 	mutex_lock(&local->iflist_mtx);
 	list_for_each_entry_safe(sdata, tmp, &local->interfaces, list) {
 		list_del(&sdata->list);
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 513627896204..68db2a356443 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1198,7 +1198,6 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 	rtnl_unlock();
 	ieee80211_led_exit(local);
 	ieee80211_wep_free(local);
-	ieee80211_txq_teardown_flows(local);
  fail_flows:
 	destroy_workqueue(local->workqueue);
  fail_workqueue:
@@ -1224,7 +1223,6 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
 #if IS_ENABLED(CONFIG_IPV6)
 	unregister_inet6addr_notifier(&local->ifa6_notifier);
 #endif
-	ieee80211_txq_teardown_flows(local);
 
 	rtnl_lock();
 
-- 
2.19.1