Re: [PATCH v3] nvdimm: btt_devs: fix a NULL pointer dereference

[Dan Williams]

On Mon, Mar 25, 2019 at 2:36 PM Aditya Pakki <pakki001@xxxxxxx> wrote:
>
> In case kmemdup fails, the fix releases resources and returns to
> avoid the NULL pointer dereference.
>
> Signed-off-by: Aditya Pakki <pakki001@xxxxxxx>
>
> ---
> v2: Replace incorrect kfree with ida_simple_remove, suggested by
> Johannes Thumshirn
> v1: Free nd_btt->id in case of failure and avoid double free, suggested
> by Dan Williams
> ---
>  drivers/nvdimm/btt_devs.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
> index b72a303176c7..f73fb5fdc93f 100644
> --- a/drivers/nvdimm/btt_devs.c
> +++ b/drivers/nvdimm/btt_devs.c
> @@ -204,8 +204,11 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
>         }
>
>         nd_btt->lbasize = lbasize;
> -       if (uuid)
> +       if (uuid) {
>                 uuid = kmemdup(uuid, 16, GFP_KERNEL);
> +               if (!uuid)
> +                       goto out_put_id;
> +       }
>         nd_btt->uuid = uuid;
>         dev = &nd_btt->dev;
>         dev_set_name(dev, "btt%d.%d", nd_region->id, nd_btt->id);
> @@ -220,6 +223,11 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
>                 return NULL;
>         }
>         return dev;
> +
> +out_put_id:
> +       ida_simple_remove(&nd_region->btt_ida, nd_btt->id);
> +       kfree(nd_btt);

There's still 2 calls to "kfree(nd_btt)" when only one is needed.
Please route them both to the same call.