[PATCH 4.4 16/23] nilfs2: fix NULL pointer in nilfs_##name##_attr_release

Greg Kroah-Hartman
2021-09-24T12:44:56Z

From: Nanyong Sun <sunnanyong@huawei.com>

[ Upstream commit dbc6e7d44a514f231a64d9d5676e001b660b6448 ]

In nilfs_##name##_attr_release, kobj->parent should not be referenced
because it is a NULL pointer. The release() method of kobject is always
called in kobject_put(kobj), in the implementation of kobject_put(), the
kobj->parent will be assigned as NULL before call the release() method.
So just use kobj to get the subgroups, which is more efficient and can fix
a NULL pointer reference problem.

Link: https://lkml.kernel.org/r/20210629022556.3985106-3-sunnanyong@huawei.com
Link: https://lkml.kernel.org/r/1625651306-10829-3-git-send-email-konishi.ryusuke@gmail.com
Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@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 | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
index 69a8f302170e..d7d6791c408e 100644
--- a/fs/nilfs2/sysfs.c
+++ b/fs/nilfs2/sysfs.c
@@ -73,11 +73,9 @@ static const struct sysfs_ops nilfs_##name##_attr_ops = { \
#define NILFS_DEV_INT_GROUP_TYPE(name, parent_name) \
static void nilfs_##name##_attr_release(struct kobject *kobj) \
{ \
- struct nilfs_sysfs_##parent_name##_subgroups *subgroups; \
- struct the_nilfs *nilfs = container_of(kobj->parent, \
- struct the_nilfs, \
- ns_##parent_name##_kobj); \
- subgroups = nilfs->ns_##parent_name##_subgroups; \
+ struct nilfs_sysfs_##parent_name##_subgroups *subgroups = container_of(kobj, \
+ struct nilfs_sysfs_##parent_name##_subgroups, \
+ sg_##name##_kobj); \
complete(&subgroups->sg_##name##_kobj_unregister); \
} \
static struct kobj_type nilfs_##name##_ktype = { \
--
2.33.0