cfg80211: fix management registrations locking

The management registrations locking was broken, the list was
locked for each wdev, but cfg80211_mgmt_registrations_update()
iterated it without holding all the correct spinlocks, causing
list corruption.

Rather than trying to fix it with fine-grained locking, just
move the lock to the wiphy/rdev (still need the list on each
wdev), we already need to hold the wdev lock to change it, so
there's no contention on the lock in any case. This trivially
fixes the bug since we hold one wdev's lock already, and now
will hold the lock that protects all lists.

Cc: stable@vger.kernel.org
Reported-by: Jouni Malinen <j@w1.fi>
Fixes: 6cd536fe62ef ("cfg80211: change internal management frame registration API")
Link: https://lore.kernel.org/r/20211025133111.5cf733eab0f4.I7b0abb0494ab712f74e2efcd24bb31ac33f7eee9@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 14 insertions, 12 deletions

diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index 3aa69b375a10..783acd2c4211 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -452,9 +452,9 @@ static void cfg80211_mgmt_registrations_update(struct wireless_dev *wdev)
 
 	lockdep_assert_held(&rdev->wiphy.mtx);
 
-	spin_lock_bh(&wdev->mgmt_registrations_lock);
+	spin_lock_bh(&rdev->mgmt_registrations_lock);
 	if (!wdev->mgmt_registrations_need_update) {
-		spin_unlock_bh(&wdev->mgmt_registrations_lock);
+		spin_unlock_bh(&rdev->mgmt_registrations_lock);
 		return;
 	}
 
@@ -479,7 +479,7 @@ static void cfg80211_mgmt_registrations_update(struct wireless_dev *wdev)
 	rcu_read_unlock();
 
 	wdev->mgmt_registrations_need_update = 0;
-	spin_unlock_bh(&wdev->mgmt_registrations_lock);
+	spin_unlock_bh(&rdev->mgmt_registrations_lock);
 
 	rdev_update_mgmt_frame_registrations(rdev, wdev, &upd);
 }
@@ -503,6 +503,7 @@ int cfg80211_mlme_register_mgmt(struct wireless_dev *wdev, u32 snd_portid,
 				int match_len, bool multicast_rx,
 				struct netlink_ext_ack *extack)
 {
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
 	struct cfg80211_mgmt_registration *reg, *nreg;
 	int err = 0;
 	u16 mgmt_type;
@@ -548,7 +549,7 @@ int cfg80211_mlme_register_mgmt(struct wireless_dev *wdev, u32 snd_portid,
 	if (!nreg)
 		return -ENOMEM;
 
-	spin_lock_bh(&wdev->mgmt_registrations_lock);
+	spin_lock_bh(&rdev->mgmt_registrations_lock);
 
 	list_for_each_entry(reg, &wdev->mgmt_registrations, list) {
 		int mlen = min(match_len, reg->match_len);
@@ -583,7 +584,7 @@ int cfg80211_mlme_register_mgmt(struct wireless_dev *wdev, u32 snd_portid,
 		list_add(&nreg->list, &wdev->mgmt_registrations);
 	}
 	wdev->mgmt_registrations_need_update = 1;
-	spin_unlock_bh(&wdev->mgmt_registrations_lock);
+	spin_unlock_bh(&rdev->mgmt_registrations_lock);
 
 	cfg80211_mgmt_registrations_update(wdev);
 
@@ -591,7 +592,7 @@ int cfg80211_mlme_register_mgmt(struct wireless_dev *wdev, u32 snd_portid,
 
  out:
 	kfree(nreg);
-	spin_unlock_bh(&wdev->mgmt_registrations_lock);
+	spin_unlock_bh(&rdev->mgmt_registrations_lock);
 
 	return err;
 }
@@ -602,7 +603,7 @@ void cfg80211_mlme_unregister_socket(struct wireless_dev *wdev, u32 nlportid)
 	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
 	struct cfg80211_mgmt_registration *reg, *tmp;
 
-	spin_lock_bh(&wdev->mgmt_registrations_lock);
+	spin_lock_bh(&rdev->mgmt_registrations_lock);
 
 	list_for_each_entry_safe(reg, tmp, &wdev->mgmt_registrations, list) {
 		if (reg->nlportid != nlportid)
@@ -615,7 +616,7 @@ void cfg80211_mlme_unregister_socket(struct wireless_dev *wdev, u32 nlportid)
 		schedule_work(&rdev->mgmt_registrations_update_wk);
 	}
 
-	spin_unlock_bh(&wdev->mgmt_registrations_lock);
+	spin_unlock_bh(&rdev->mgmt_registrations_lock);
 
 	if (nlportid && rdev->crit_proto_nlportid == nlportid) {
 		rdev->crit_proto_nlportid = 0;
@@ -628,15 +629,16 @@ void cfg80211_mlme_unregister_socket(struct wireless_dev *wdev, u32 nlportid)
 
 void cfg80211_mlme_purge_registrations(struct wireless_dev *wdev)
 {
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
 	struct cfg80211_mgmt_registration *reg, *tmp;
 
-	spin_lock_bh(&wdev->mgmt_registrations_lock);
+	spin_lock_bh(&rdev->mgmt_registrations_lock);
 	list_for_each_entry_safe(reg, tmp, &wdev->mgmt_registrations, list) {
 		list_del(&reg->list);
 		kfree(reg);
 	}
 	wdev->mgmt_registrations_need_update = 1;
-	spin_unlock_bh(&wdev->mgmt_registrations_lock);
+	spin_unlock_bh(&rdev->mgmt_registrations_lock);
 
 	cfg80211_mgmt_registrations_update(wdev);
 }
@@ -784,7 +786,7 @@ bool cfg80211_rx_mgmt_khz(struct wireless_dev *wdev, int freq, int sig_dbm,
 	data = buf + ieee80211_hdrlen(mgmt->frame_control);
 	data_len = len - ieee80211_hdrlen(mgmt->frame_control);
 
-	spin_lock_bh(&wdev->mgmt_registrations_lock);
+	spin_lock_bh(&rdev->mgmt_registrations_lock);
 
 	list_for_each_entry(reg, &wdev->mgmt_registrations, list) {
 		if (reg->frame_type != ftype)
@@ -808,7 +810,7 @@ bool cfg80211_rx_mgmt_khz(struct wireless_dev *wdev, int freq, int sig_dbm,
 		break;
 	}
 
-	spin_unlock_bh(&wdev->mgmt_registrations_lock);
+	spin_unlock_bh(&rdev->mgmt_registrations_lock);
 
 	trace_cfg80211_return_bool(result);
 	return result;