From: Tejun Heo <tj@kernel.org>
To: Hillf Danton <hdanton@sina.com>
Cc: syzbot <syzbot+38f5d5cf7ae88c46b11a@syzkaller.appspotmail.com>,
gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: WARNING in kernfs_create_dir_ns
Date: Mon, 8 Jul 2019 07:46:32 -0700 [thread overview]
Message-ID: <20190708144632.GB657710@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <0000000000003bbf1b058c83f55a@google.com>
Hello,
On Mon, Jul 01, 2019 at 01:52:35PM +0800, Hillf Danton wrote:
> >WARNING: CPU: 0 PID: 8613 at fs/kernfs/dir.c:493 kernfs_get fs/kernfs/dir.c:493 [inline]
> >WARNING: CPU: 0 PID: 8613 at fs/kernfs/dir.c:493 kernfs_new_node fs/kernfs/dir.c:700 [inline]
> >WARNING: CPU: 0 PID: 8613 at fs/kernfs/dir.c:493 kernfs_create_dir_ns+0x205/0x230 fs/kernfs/dir.c:1022
...
> --- a/fs/sysfs/dir.c
> +++ b/fs/sysfs/dir.c
> @@ -53,6 +53,10 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
> if (!parent)
> return -ENOENT;
>
> + /* create dir if parent is not dying */
> + if (!atomic_inc_not_zero(&parent->count))
> + return -ENOENT;
> +
> kobject_get_ownership(kobj, &uid, &gid);
>
> kn = kernfs_create_dir_ns(parent, kobject_name(kobj),
> @@ -61,10 +65,12 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
> if (IS_ERR(kn)) {
> if (PTR_ERR(kn) == -EEXIST)
> sysfs_warn_dup(parent, kobject_name(kobj));
> + kernfs_put(parent);
> return PTR_ERR(kn);
> }
>
> kobj->sd = kn;
> + kernfs_put(parent);
I don't think this is the correct fix. It's being called with kobj
whose parent's sysfs node is dangling. It gotta be fixed from the
caller side.
Thanks.
--
tejun
next prev parent reply other threads:[~2019-07-08 14:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-29 13:12 WARNING in kernfs_create_dir_ns syzbot
2019-06-30 5:41 ` syzbot
2019-07-08 14:46 ` Tejun Heo [this message]
2019-06-30 10:40 ` syzbot
2020-04-16 0:11 ` syzbot
2020-04-16 0:30 ` Waiman Long
[not found] <20190709022335.12928-1-hdanton@sina.com>
2019-07-09 14:22 ` Tejun Heo
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