linux-kernel - [PATCH 4.9 69/71] nilfs2: fix memory leak in nilfs_sysfs_delete_device

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Date:   Mon, 28 Jun 2021 10:40:01 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Pavel Skripkin <paskripkin@...il.com>,
        Ryusuke Konishi <konishi.ryusuke@...il.com>,
        "Michael L . Semon" <mlsemon35@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 69/71] nilfs2: fix memory leak in nilfs_sysfs_delete_device_group

From: Pavel Skripkin <paskripkin@...il.com>

[ Upstream commit 8fd0c1b0647a6bda4067ee0cd61e8395954b6f28 ]

My local syzbot instance hit memory leak in nilfs2.  The problem was in
missing kobject_put() in nilfs_sysfs_delete_device_group().

kobject_del() does not call kobject_cleanup() for passed kobject and it
leads to leaking duped kobject name if kobject_put() was not called.

Fail log:

  BUG: memory leak
  unreferenced object 0xffff8880596171e0 (size 8):
  comm "syz-executor379", pid 8381, jiffies 4294980258 (age 21.100s)
  hex dump (first 8 bytes):
    6c 6f 6f 70 30 00 00 00                          loop0...
  backtrace:
     kstrdup+0x36/0x70 mm/util.c:60
     kstrdup_const+0x53/0x80 mm/util.c:83
     kvasprintf_const+0x108/0x190 lib/kasprintf.c:48
     kobject_set_name_vargs+0x56/0x150 lib/kobject.c:289
     kobject_add_varg lib/kobject.c:384 [inline]
     kobject_init_and_add+0xc9/0x160 lib/kobject.c:473
     nilfs_sysfs_create_device_group+0x150/0x800 fs/nilfs2/sysfs.c:999
     init_nilfs+0xe26/0x12b0 fs/nilfs2/the_nilfs.c:637

Link: https://lkml.kernel.org/r/20210612140559.20022-1-paskripkin@gmail.com
Fixes: da7141fb78db ("nilfs2: add /sys/fs/nilfs2/<device> group")
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@...il.com>
Cc: Michael L. Semon <mlsemon35@...il.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/nilfs2/sysfs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
index 490303e3d517..e9903bceb2bf 100644
--- a/fs/nilfs2/sysfs.c
+++ b/fs/nilfs2/sysfs.c
@@ -1064,6 +1064,7 @@ void nilfs_sysfs_delete_device_group(struct the_nilfs *nilfs)
 	nilfs_sysfs_delete_superblock_group(nilfs);
 	nilfs_sysfs_delete_segctor_group(nilfs);
 	kobject_del(&nilfs->ns_dev_kobj);
+	kobject_put(&nilfs->ns_dev_kobj);
 	kfree(nilfs->ns_dev_subgroups);
 }
 
-- 
2.30.2