Re: [PATCH] mm/hugetlb: Fix potential double free in hugetlb_register_node() error path

[Muchun Song <smuchun@gmail.com>]

On Thu, Jan 7, 2021 at 8:36 PM Miaohe Lin <linmiaohe@huawei.com> wrote:
>
> In hugetlb_sysfs_add_hstate(), we would do kobject_put() on hstate_kobjs
> when failed to create sysfs group but forget to set hstate_kobjs to NULL.
> Then in hugetlb_register_node() error path, we may free it again via
> hugetlb_unregister_node().
>
> Fixes: a3437870160c ("hugetlb: new sysfs interface")
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> Cc: <stable@vger.kernel.org>
> ---
>  mm/hugetlb.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Reviewed-by: Muchun Song <smuchun@gmail.com>

>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index e249bffa0e75..91a2a2025a2c 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2947,8 +2947,10 @@ static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
>                 return -ENOMEM;
>
>         retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
> -       if (retval)
> +       if (retval) {
>                 kobject_put(hstate_kobjs[hi]);
> +               hstate_kobjs[hi] = NULL;
> +       }
>
>         return retval;
>  }
> --
> 2.19.1
>