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

commit 517879147493a5e1df6b89a50f708f1133fcaddb upstream.

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.

Reported-by: syzbot+4ece1a28b8f4730547c9@syzkaller.appspotmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 1ab5e1a51c98a21440fb275a2fdd31e0e7982882..607d8fdd5e68f768f7e022542f2485dd147a1ef5 100644 (file)
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -735,7 +735,7 @@ 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);