linux-kernel - [PATCH] kobject: Safe return of kobject_get

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Message-ID: <CWXP265MB2680094534A5559B0A904B76C4089@CWXP265MB2680.GBRP265.PROD.OUTLOOK.COM>
Date:   Wed, 23 Jun 2021 14:47:35 +0000
From:   Christian Löhle <CLoehle@...erstone.com>
To:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Christian Löhle <CLoehle@...erstone.com>
CC:     "rafael@...nel.org" <rafael@...nel.org>
Subject: [PATCH] kobject: Safe return of kobject_get_path with NULL

Prevent NULL dereference within get_kobj_path_length

Calling kobject_get_path could provoke a NULL dereference
if NULL was passed. while fill_kobj_path will return
with a sane 0 for NULL, kobjet_get_path_length did not.

Signed-off-by: Christian Loehle <cloehle@...erstone.com>
---
 lib/kobject.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/kobject.c b/lib/kobject.c
index ea53b30cf483..735159c13a94 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -130,6 +130,8 @@ static int get_kobj_path_length(struct kobject *kobj)
 {
 	int length = 1;
 	struct kobject *parent = kobj;
+	if (!kobj)
+		return 0;
 
 	/* walk up the ancestors until we hit the one pointing to the
 	 * root.
-- 
2.32.0

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