linux-kernel - [PATCH 5.4 095/132] kobject: Restore old behaviour of kobject

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Message-Id: <20200915140648.902771537@linuxfoundation.org>
Date:   Tue, 15 Sep 2020 16:13:17 +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, Qu Wenruo <quwenruo.btrfs@....com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Qu Wenruo <wqu@...e.com>
Subject: [PATCH 5.4 095/132] kobject: Restore old behaviour of kobject_del(NULL)

From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

commit 40b8b826a6998639dd1c26f0e127f18371e1058d upstream.

The commit 079ad2fb4bf9 ("kobject: Avoid premature parent object freeing in
kobject_cleanup()") inadvertently dropped a possibility to call kobject_del()
with NULL pointer. Restore the old behaviour.

Fixes: 079ad2fb4bf9 ("kobject: Avoid premature parent object freeing in kobject_cleanup()")
Cc: stable <stable@...r.kernel.org>
Reported-by: Qu Wenruo <quwenruo.btrfs@....com>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Reviewed-by: Qu Wenruo <wqu@...e.com>
Link: https://lore.kernel.org/r/20200803082706.65347-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 lib/kobject.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -630,8 +630,12 @@ static void __kobject_del(struct kobject
  */
 void kobject_del(struct kobject *kobj)
 {
-	struct kobject *parent = kobj->parent;
+	struct kobject *parent;
 
+	if (!kobj)
+		return;
+
+	parent = kobj->parent;
 	__kobject_del(kobj);
 	kobject_put(parent);
 }