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Subject[PATCH net-next 1/3] net: ipvlan: fix potential UAF problem for phy_dev
Date
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.

That likes as the scenario occurred by
commit 563bcbae3ba2 ("net: vlan: fix a UAF in vlan_dev_real_dev()").

Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
---
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
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