On Mon, Mar 14, 2022 at 3:54 AM Ziyang Xuan
<[email protected]> wrote:
>
> Add the reference operation to phy_dev of ipvlan to avoid
> the potential UAF problem under the following known scenario:
>
> Someone module puts the NETDEV_UNREGISTER event handler to a
> work, and phy_dev is accessed in the work handler. But when
> the work is excuted, phy_dev has been destroyed because upper
> ipvlan did not get reference to phy_dev correctly.
Can you name the module deferring NETDEV_UNREGISTER to a work queue ?
This sounds like a bug to me.
>
> That likes as the scenario occurred by
> commit 563bcbae3ba2 ("net: vlan: fix a UAF in vlan_dev_real_dev()").
Mentioning a commit that added a bug and many other commits trying to
fix it is a bit unfortunate.
Can you instead add a Fixes: tag ?
Do you have a repro to trigger the bug ?
>
> Signed-off-by: Ziyang Xuan <[email protected]>
> ---
> drivers/net/ipvlan/ipvlan_main.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
> index 696e245f6d00..dcdc01403f22 100644
> --- a/drivers/net/ipvlan/ipvlan_main.c
> +++ b/drivers/net/ipvlan/ipvlan_main.c
> @@ -158,6 +158,10 @@ static int ipvlan_init(struct net_device *dev)
> }
> port = ipvlan_port_get_rtnl(phy_dev);
> port->count += 1;
> +
> + /* Get ipvlan's reference to phy_dev */
> + dev_hold(phy_dev);
> +
> return 0;
> }
>
> @@ -665,6 +669,14 @@ void ipvlan_link_delete(struct net_device *dev, struct list_head *head)
> }
> EXPORT_SYMBOL_GPL(ipvlan_link_delete);
>
> +static void ipvlan_dev_free(struct net_device *dev)
> +{
> + struct ipvl_dev *ipvlan = netdev_priv(dev);
> +
> + /* Get rid of the ipvlan's reference to phy_dev */
> + dev_put(ipvlan->phy_dev);
> +}
> +
> void ipvlan_link_setup(struct net_device *dev)
> {
> ether_setup(dev);
> @@ -674,6 +686,7 @@ void ipvlan_link_setup(struct net_device *dev)
> dev->priv_flags |= IFF_UNICAST_FLT | IFF_NO_QUEUE;
> dev->netdev_ops = &ipvlan_netdev_ops;
> dev->needs_free_netdev = true;
> + dev->priv_destructor = ipvlan_dev_free;
> dev->header_ops = &ipvlan_header_ops;
> dev->ethtool_ops = &ipvlan_ethtool_ops;
> }
> --
> 2.25.1
>