Re: [syzbot] [fs?] KASAN: slab-use-after-free Read in lockref_get

[Edward Adam Davis]

before remove debugfs_dir set reference pointer to NULL

#syz test: linux-next 58f9416d413a

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 68596ef78b15..b9961edf6fa5 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -1019,8 +1019,10 @@ void ieee80211_debugfs_remove_netdev(struct ieee80211_sub_if_data *sdata)
 	if (!sdata->vif.debugfs_dir)
 		return;
 
-	debugfs_remove_recursive(sdata->vif.debugfs_dir);
+	struct dentry *debugfs_dir = sdata->vif.debugfs_dir;
+
 	sdata->vif.debugfs_dir = NULL;
+	debugfs_remove_recursive(debugfs_dir);
 	sdata->debugfs.subdir_stations = NULL;
 }
 
diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c
index 1e9389c49a57..357f310ec75f 100644
--- a/net/mac80211/debugfs_sta.c
+++ b/net/mac80211/debugfs_sta.c
@@ -1284,6 +1284,11 @@ void ieee80211_sta_debugfs_add(struct sta_info *sta)
 
 void ieee80211_sta_debugfs_remove(struct sta_info *sta)
 {
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+
+	if (!sdata->vif.debugfs_dir)
+		return;
+
 	debugfs_remove_recursive(sta->debugfs_dir);
 	sta->debugfs_dir = NULL;
 }