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: [email protected]
Reported-by: Jouni Malinen <[email protected]>
Fixes: 6cd536f ("cfg80211: change internal management frame registration API")
Link: https://lore.kernel.org/r/20211025133111.5cf733eab0f4.I7b0abb0494ab712f74e2efcd24bb31ac33f7eee9@changeid
Signed-off-by: Johannes Berg <[email protected]>

Author: jmberg-intel

include/net/cfg80211.h

@@ -5376,7 +5376,6 @@ static inline void wiphy_unlock(struct wiphy *wiphy)
  *	netdev and may otherwise be used by driver read-only, will be update
  *	by cfg80211 on change_interface
  * @mgmt_registrations: list of registrations for management frames
- * @mgmt_registrations_lock: lock for the list
  * @mgmt_registrations_need_update: mgmt registrations were updated,
  *	need to propagate the update to the driver
  * @mtx: mutex used to lock data in this struct, may be used by drivers
@@ -5423,7 +5422,6 @@ struct wireless_dev {
 	u32 identifier;
 
 	struct list_head mgmt_registrations;
-	spinlock_t mgmt_registrations_lock;
 	u8 mgmt_registrations_need_update:1;
 
 	struct mutex mtx;

net/wireless/core.c

@@ -524,6 +524,7 @@ struct wiphy *wiphy_new_nm(const struct cfg80211_ops *ops, int sizeof_priv,
 	INIT_WORK(&rdev->propagate_cac_done_wk, cfg80211_propagate_cac_done_wk);
 	INIT_WORK(&rdev->mgmt_registrations_update_wk,
 		  cfg80211_mgmt_registrations_update_wk);
+	spin_lock_init(&rdev->mgmt_registrations_lock);
 
 #ifdef CONFIG_CFG80211_DEFAULT_PS
 	rdev->wiphy.flags |= WIPHY_FLAG_PS_ON_BY_DEFAULT;
@@ -1279,7 +1280,6 @@ void cfg80211_init_wdev(struct wireless_dev *wdev)
 	INIT_LIST_HEAD(&wdev->event_list);
 	spin_lock_init(&wdev->event_lock);
 	INIT_LIST_HEAD(&wdev->mgmt_registrations);
-	spin_lock_init(&wdev->mgmt_registrations_lock);
 	INIT_LIST_HEAD(&wdev->pmsr_list);
 	spin_lock_init(&wdev->pmsr_lock);
 	INIT_WORK(&wdev->pmsr_free_wk, cfg80211_pmsr_free_wk);

net/wireless/core.h

@@ -100,6 +100,8 @@ struct cfg80211_registered_device {
 	struct work_struct propagate_cac_done_wk;
 
 	struct work_struct mgmt_registrations_update_wk;
+	/* lock for all wdev lists */
+	spinlock_t mgmt_registrations_lock;
 
 	/* must be last because of the way we do wiphy_priv(),
 	 * and it should at least be aligned to NETDEV_ALIGN */

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);
@@ -583,15 +584,15 @@ 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);
 
 	return 0;
 
  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;