linux-kernel - [PATCH 5.17 0285/1126] fs: erofs: add sanity check for kobject in erofs_unregister

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Date:   Tue,  5 Apr 2022 09:17:12 +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, Dongliang Mu <mudongliangabcd@...il.com>,
        Gao Xiang <hsiangkao@...ux.alibaba.com>,
        Chao Yu <chao@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.17 0285/1126] fs: erofs: add sanity check for kobject in erofs_unregister_sysfs

From: Dongliang Mu <mudongliangabcd@...il.com>

[ Upstream commit a942da24abc5839c11a8fc2a4b7cb268ea94ba54 ]

Syzkaller hit 'WARNING: kobject bug in erofs_unregister_sysfs'. This bug
is triggered by injecting fault in kobject_init_and_add of
erofs_unregister_sysfs.

Fix this by adding sanity check for kobject in erofs_unregister_sysfs

Note that I've tested the patch and the crash does not occur any more.

Link: https://lore.kernel.org/r/20220315132814.12332-1-dzm91@hust.edu.cn
Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com>
Fixes: 168e9a76200c ("erofs: add sysfs interface")
Reviewed-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
Reviewed-by: Chao Yu <chao@...nel.org>
Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/erofs/sysfs.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
index dac252bc9228..f3babf1e6608 100644
--- a/fs/erofs/sysfs.c
+++ b/fs/erofs/sysfs.c
@@ -221,9 +221,11 @@ void erofs_unregister_sysfs(struct super_block *sb)
 {
 	struct erofs_sb_info *sbi = EROFS_SB(sb);
 
-	kobject_del(&sbi->s_kobj);
-	kobject_put(&sbi->s_kobj);
-	wait_for_completion(&sbi->s_kobj_unregister);
+	if (sbi->s_kobj.state_in_sysfs) {
+		kobject_del(&sbi->s_kobj);
+		kobject_put(&sbi->s_kobj);
+		wait_for_completion(&sbi->s_kobj_unregister);
+	}
 }
 
 int __init erofs_init_sysfs(void)
-- 
2.34.1