From 0bbab5f0301587cad4e923ccc49bb910db86162c Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Mon, 25 May 2020 11:38:17 +0200
Subject: [PATCH] cfg80211: fix debugfs rename crash
Git-commit: 0bbab5f0301587cad4e923ccc49bb910db86162c
Patch-mainline: v5.7
References: jsc#SLE-13430

Removing the "if (IS_ERR(dir)) dir = NULL;" check only works
if we adjust the remaining code to not rely on it being NULL.
Check IS_ERR_OR_NULL() before attempting to dereference it.

I'm not actually entirely sure this fixes the syzbot crash as
the kernel config indicates that they do have DEBUG_FS in the
kernel, but this is what I found when looking there.

Cc: stable@vger.kernel.org
Fixes: d82574a8e5a4 ("cfg80211: no need to check return value of debugfs_create functions")
Reported-by: syzbot+fd5332e429401bf42d18@syzkaller.appspotmail.com
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200525113816.fc4da3ec3d4b.Ica63a110679819eaa9fb3bc1b7437d96b1fd187d@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

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

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 341402b4f178..ce024440fa51 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -142,7 +142,7 @@ int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
 	if (result)
 		return result;
 
-	if (rdev->wiphy.debugfsdir)
+	if (!IS_ERR_OR_NULL(rdev->wiphy.debugfsdir))
 		debugfs_rename(rdev->wiphy.debugfsdir->d_parent,
 			       rdev->wiphy.debugfsdir,
 			       rdev->wiphy.debugfsdir->d_parent, newname);
-- 
2.16.4