linux-kernel - Re: [PATCH V2] nilfs2: Fix reference count leak in nilfs_sysfs_create_device

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Date:   Thu, 28 May 2020 08:23:34 +0900
From:   Ryusuke Konishi <konishi.ryusuke@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-nilfs <linux-nilfs@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, kjlu@....edu,
        Vyacheslav Dubeyko <Vyacheslav.Dubeyko@...t.com>,
        wu000273@....edu
Subject: Re: [PATCH V2] nilfs2: Fix reference count leak in nilfs_sysfs_create_device_group

Hi Andrew,

Please pick this up as well.

Acked-by: Ryusuke Konishi <konishi.ryusuke@...il.com>

On Thu, May 28, 2020 at 8:04 AM <wu000273@....edu> wrote:
>
> From: Qiushi Wu <wu000273@....edu>
>
> kobject_init_and_add() takes reference even when it fails.
> In nilfs_sysfs_create_device_group(), the memory allocated by
> kobject_init_and_add() is not freed when kobject_init_and_add()
> fails. Fix this issue by calling kobject_put() to clean up the
> kobject.
>
> Fixes: da7141fb78db ("nilfs2: add /sys/fs/nilfs2/<device> group")
> Signed-off-by: Qiushi Wu <wu000273@....edu>
> ---
>  V2: using kobject_put() to handle kobject_init_and_add() instead of
>  kobject_del().
>
>  fs/nilfs2/sysfs.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
> index e60be7bb55b0..8416f915d118 100644
> --- a/fs/nilfs2/sysfs.c
> +++ b/fs/nilfs2/sysfs.c
> @@ -999,8 +999,10 @@ int nilfs_sysfs_create_device_group(struct super_block *sb)
>         init_completion(&nilfs->ns_dev_kobj_unregister);
>         err = kobject_init_and_add(&nilfs->ns_dev_kobj, &nilfs_dev_ktype, NULL,
>                                     "%s", sb->s_id);
> -       if (err)
> +       if (err) {
> +               kobject_put(&nilfs->ns_dev_kobj);
>                 goto free_dev_subgroups;
> +       }
>
>         err = nilfs_sysfs_create_mounted_snapshots_group(nilfs);
>         if (err)
> --
> 2.17.1
>