netdev - Re: [PATCH net] net: openvswitch: fix possible memleak on create vport fails

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Date:   Sat, 21 Sep 2019 20:17:00 -0700
From:   Pravin Shelar <pshelar@....org>
To:     Tonghao Zhang <xiangxia.m.yue@...il.com>,
        Hillf Danton <hdanton@...a.com>
Cc:     Greg Rose <gvrose8192@...il.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Taehee Yoo <ap420073@...il.com>
Subject: Re: [PATCH net] net: openvswitch: fix possible memleak on create
 vport fails

On Sat, Sep 21, 2019 at 8:07 AM <xiangxia.m.yue@...il.com> wrote:
>
> From: Tonghao Zhang <xiangxia.m.yue@...il.com>
>
> If we register a net device which name is not valid
> (dev_get_valid_name), register_netdevice will return err
> codes and will not run dev->priv_destructor. The memory
> will leak. This patch adds check in ovs_vport_free and
> set the vport NULL.
>
> Fixes: 309b66970ee2 ("net: openvswitch: do not free vport if register_netdevice() is failed.")
> Cc: Taehee Yoo <ap420073@...il.com>
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@...il.com>
> ---
>  net/openvswitch/vport-internal_dev.c | 8 ++------
>  net/openvswitch/vport.c              | 9 +++++++++
>  2 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/net/openvswitch/vport-internal_dev.c b/net/openvswitch/vport-internal_dev.c
> index d2437b5..074c43f 100644
> --- a/net/openvswitch/vport-internal_dev.c
> +++ b/net/openvswitch/vport-internal_dev.c
> @@ -159,7 +159,6 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
>         struct internal_dev *internal_dev;
>         struct net_device *dev;
>         int err;
> -       bool free_vport = true;
>
>         vport = ovs_vport_alloc(0, &ovs_internal_vport_ops, parms);
>         if (IS_ERR(vport)) {
> @@ -190,10 +189,8 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
>
>         rtnl_lock();
>         err = register_netdevice(vport->dev);
> -       if (err) {
> -               free_vport = false;
> +       if (err)
>                 goto error_unlock;
> -       }
>
>         dev_set_promiscuity(vport->dev, 1);
>         rtnl_unlock();
> @@ -207,8 +204,7 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
>  error_free_netdev:
>         free_netdev(dev);
>  error_free_vport:
> -       if (free_vport)
> -               ovs_vport_free(vport);
> +       ovs_vport_free(vport);
>  error:
>         return ERR_PTR(err);
>  }
> diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
> index 3fc38d1..281259a 100644
> --- a/net/openvswitch/vport.c
> +++ b/net/openvswitch/vport.c
> @@ -157,11 +157,20 @@ struct vport *ovs_vport_alloc(int priv_size, const struct vport_ops *ops,
>   */
>  void ovs_vport_free(struct vport *vport)
>  {
> +       /* We should check whether vport is NULL.
> +        * We may free it again, for example in internal_dev_create
> +        * if register_netdevice fails, vport may have been freed via
> +        * internal_dev_destructor.
> +        */
> +       if (unlikely(!vport))
> +               return;
> +
>         /* vport is freed from RCU callback or error path, Therefore
>          * it is safe to use raw dereference.
>          */
>         kfree(rcu_dereference_raw(vport->upcall_portids));
>         kfree(vport);
> +       vport = NULL;
>  }
>  EXPORT_SYMBOL_GPL(ovs_vport_free);
>
> --

There is already patch a patch to fix this memory leak.
https://patchwork.ozlabs.org/patch/1144316/
Can you or Hillf post it on netdev list?

Thanks.