From 53e96d05e45a2e507551b48ccc18ac82872bf9df Mon Sep 17 00:00:00 2001 From: Ziyang Xuan Date: Fri, 11 Mar 2022 17:03:26 +0800 Subject: [PATCH] net: macvlan: fix potential UAF problem for lowerdev Add the reference operation to lowerdev of macvlan to avoid the potential UAF problem under the following known scenario: Someone module puts the NETDEV_UNREGISTER event handler to a work, and lowerdev is accessed in the work handler. But when the work is excuted, lowerdev has been destroyed because upper macvlan did not get reference to lowerdev correctly. That likes as the scenario occurred by commit 52f553199741 ("net: vlan: fix a UAF in vlan_dev_real_dev()"). Signed-off-by: Ziyang Xuan Signed-off-by: David S. Miller --- drivers/net/macvlan.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c index 4b77819e93281..b339581e36aad 100644 --- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -889,7 +889,7 @@ static void macvlan_set_lockdep_class(struct net_device *dev) static int macvlan_init(struct net_device *dev) { struct macvlan_dev *vlan = netdev_priv(dev); - const struct net_device *lowerdev = vlan->lowerdev; + struct net_device *lowerdev = vlan->lowerdev; struct macvlan_port *port = vlan->port; dev->state = (dev->state & ~MACVLAN_STATE_MASK) | @@ -911,6 +911,9 @@ static int macvlan_init(struct net_device *dev) port->count += 1; + /* Get macvlan's reference to lowerdev */ + dev_hold(lowerdev); + return 0; } @@ -1173,6 +1176,14 @@ static const struct net_device_ops macvlan_netdev_ops = { .ndo_features_check = passthru_features_check, }; +static void macvlan_dev_free(struct net_device *dev) +{ + struct macvlan_dev *vlan = netdev_priv(dev); + + /* Get rid of the macvlan's reference to lowerdev */ + dev_put(vlan->lowerdev); +} + void macvlan_common_setup(struct net_device *dev) { ether_setup(dev); @@ -1184,6 +1195,7 @@ void macvlan_common_setup(struct net_device *dev) dev->priv_flags |= IFF_UNICAST_FLT | IFF_CHANGE_PROTO_DOWN; dev->netdev_ops = &macvlan_netdev_ops; dev->needs_free_netdev = true; + dev->priv_destructor = macvlan_dev_free; dev->header_ops = &macvlan_hard_header_ops; dev->ethtool_ops = &macvlan_ethtool_ops; } -- 2.39.5