netdev - [PATCH] net: wireless: move the deallocation of regulatory domain to wiphy

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Date:   Mon, 26 Jul 2021 19:55:53 +0800
From:   Dongliang Mu <mudongliangabcd@...il.com>
To:     Johannes Berg <johannes@...solutions.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "Luis R. Rodriguez" <lrodriguez@...eros.com>,
        "John W. Linville" <linville@...driver.com>
Cc:     Dongliang Mu <mudongliangabcd@...il.com>,
        syzbot+1638e7c770eef6b6c0d0@...kaller.appspotmail.com,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] net: wireless: move the deallocation of regulatory domain to wiphy_free

If wiphy_register fails or does not get called, which leads to
that, ieee80211_register_hw returns with an error. Then the error
handling code of mac80211_hwsim_new_radio does not free wiphy->regd.
Note that, the free stack trace of wiphy->regd is as follows:

ieee80211_unregister_hw()
  -> wiphy_unregister()
    -> wiphy_regulatory_deregister()
      -> rcu_free_regdom()

Fix this by moving the free operation of regd from wiphy_unregister to
wiphy_free.

Reported-by: syzbot+1638e7c770eef6b6c0d0@...kaller.appspotmail.com
Fixes: 3e0c3ff36c4c ("cfg80211: allow multiple driver regulatory_hints()")
Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com>
---
 net/wireless/core.c | 3 +++
 net/wireless/reg.c  | 9 +++++----
 net/wireless/reg.h  | 1 +
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 03323121ca50..2cc2bdddc9e8 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1085,6 +1085,9 @@ void cfg80211_dev_free(struct cfg80211_registered_device *rdev)
 
 void wiphy_free(struct wiphy *wiphy)
 {
+	rcu_free_regdom(get_wiphy_regdom(wiphy));
+	RCU_INIT_POINTER(wiphy->regd, NULL);
+
 	put_device(&wiphy->dev);
 }
 EXPORT_SYMBOL(wiphy_free);
diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index c2d0ff7f089f..246f882e0021 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -196,12 +196,16 @@ enum nl80211_dfs_regions reg_get_dfs_region(struct wiphy *wiphy)
 	return regd->dfs_region;
 }
 
-static void rcu_free_regdom(const struct ieee80211_regdomain *r)
+/*
+ * Free the regulatory domain associated with the wiphy
+ */
+void rcu_free_regdom(const struct ieee80211_regdomain *r)
 {
 	if (!r)
 		return;
 	kfree_rcu((struct ieee80211_regdomain *)r, rcu_head);
 }
+EXPORT_SYMBOL(rcu_free_regdom);
 
 static struct regulatory_request *get_last_request(void)
 {
@@ -4064,9 +4068,6 @@ void wiphy_regulatory_deregister(struct wiphy *wiphy)
 	if (!reg_dev_ignore_cell_hint(wiphy))
 		reg_num_devs_support_basehint--;
 
-	rcu_free_regdom(get_wiphy_regdom(wiphy));
-	RCU_INIT_POINTER(wiphy->regd, NULL);
-
 	if (lr)
 		request_wiphy = wiphy_idx_to_wiphy(lr->wiphy_idx);
 
diff --git a/net/wireless/reg.h b/net/wireless/reg.h
index f3707f729024..03de4e5ece85 100644
--- a/net/wireless/reg.h
+++ b/net/wireless/reg.h
@@ -32,6 +32,7 @@ bool reg_is_valid_request(const char *alpha2);
 bool is_world_regdom(const char *alpha2);
 bool reg_supported_dfs_region(enum nl80211_dfs_regions dfs_region);
 enum nl80211_dfs_regions reg_get_dfs_region(struct wiphy *wiphy);
+void rcu_free_regdom(const struct ieee80211_regdomain *r);
 
 int regulatory_hint_user(const char *alpha2,
 			 enum nl80211_user_reg_hint_type user_reg_hint_type);
-- 
2.25.1