mac80211: don't attempt to rename ERR_PTR() debugfs dirs

We need to dereference the directory to get its parent to
be able to rename it, so it's clearly not safe to try to
do this with ERR_PTR() pointers. Skip in this case.

It seems that this is most likely what was causing the
report by syzbot, but I'm not entirely sure as it didn't
come with a reproducer this time.

Cc: stable@vger.kernel.org
Reported-by: syzbot+4ece1a28b8f4730547c9@syzkaller.appspotmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index cff0fb3578c9a41519984d266bfad2154d039c5d..deb3faf08337288b2c746be8a2863b38f6d168c7 100644 (file)
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -841,7 +841,7 @@ void ieee80211_debugfs_rename_netdev(struct ieee80211_sub_if_data *sdata)
 
        dir = sdata->vif.debugfs_dir;
 
-       if (!dir)
+       if (IS_ERR_OR_NULL(dir))
                return;
 
        sprintf(buf, "netdev:%s", sdata->name);