Re: [PATCH net-next 1/3] net: ipvlan: fix potential UAF problem for phy_dev
From: Eric Dumazet <edumazet@google.com>
Date: 2022-03-14 17:24:19
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On Mon, Mar 14, 2022 at 3:54 AM Ziyang Xuan [off-list ref] 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 ?
quoted hunk ↗ jump to hunk
Signed-off-by: Ziyang Xuan <redacted> --- 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