linux-kernel - [PATCH 4.19 03/99] mac80211: dont attempt to rename ERR

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Message-Id: <20190506143054.184704313@linuxfoundation.org>
Date:   Mon,  6 May 2019 16:31:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+4ece1a28b8f4730547c9@...kaller.appspotmail.com,
        Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH 4.19 03/99] mac80211: dont attempt to rename ERR_PTR() debugfs dirs

From: Johannes Berg <johannes.berg@...el.com>

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.

Cc: stable@...r.kernel.org
Reported-by: syzbot+4ece1a28b8f4730547c9@...kaller.appspotmail.com
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/mac80211/debugfs_netdev.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -838,7 +838,7 @@ void ieee80211_debugfs_rename_netdev(str
 
 	dir = sdata->vif.debugfs_dir;
 
-	if (!dir)
+	if (IS_ERR_OR_NULL(dir))
 		return;
 
 	sprintf(buf, "netdev:%s", sdata->name);