[PATCH 4.9 69/71] nilfs2: fix memory leak in nilfs_sysfs_delete_device_group

Sasha Levin
2021-06-28T15:23:56Z

From: Pavel Skripkin <paskripkin@gmail.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@gmail.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Michael L. Semon <mlsemon35@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.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