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Date: Mon, 21 Mar 2011 14:15:31 -0700
From: ebiederm@...ssion.com (Eric W. Biederman)
To: David Miller <davem@...emloft.net>
Cc: <netdev@...r.kernel.org>, Patrick McHardy <kaber@...sh.net>,
Ben Greear <greearb@...delatech.com>,
Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH] macvlan: Fix use after free of struct macvlan_port.
When the macvlan driver was extended to call unregisgter_netdevice_queue
in 23289a37e2b127dfc4de1313fba15bb4c9f0cd5b, a use after free of struct
macvlan_port was introduced. The code in dellink relied on unregister_netdevice
actually unregistering the net device so it would be safe to free macvlan_port.
Since unregister_netdevice_queue can just queue up the unregister instead of
performing the unregiser immediately we free the macvlan_port too soon and
then the code in macvlan_stop removes the macaddress for the set of macaddress
to listen for and uses memory that has already been freed.
To fix this add a reference count to track when it is safe to free the macvlan_port
and move the call of macvlan_port_destroy into macvlan_uninit which is guaranteed
to be called after the final macvlan_port_close.
Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>
---
drivers/net/macvlan.c | 18 ++++++++++++------
1 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 5b37d3c..78e34e9 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -39,8 +39,11 @@ struct macvlan_port {
struct list_head vlans;
struct rcu_head rcu;
bool passthru;
+ int count;
};
+static void macvlan_port_destroy(struct net_device *dev);
+
#define macvlan_port_get_rcu(dev) \
((struct macvlan_port *) rcu_dereference(dev->rx_handler_data))
#define macvlan_port_get(dev) ((struct macvlan_port *) dev->rx_handler_data)
@@ -457,8 +460,13 @@ static int macvlan_init(struct net_device *dev)
static void macvlan_uninit(struct net_device *dev)
{
struct macvlan_dev *vlan = netdev_priv(dev);
+ struct macvlan_port *port = vlan->port;
free_percpu(vlan->pcpu_stats);
+
+ port->count -= 1;
+ if (!port->count)
+ macvlan_port_destroy(port->dev);
}
static struct rtnl_link_stats64 *macvlan_dev_get_stats64(struct net_device *dev,
@@ -691,12 +699,13 @@ int macvlan_common_newlink(struct net *src_net, struct net_device *dev,
vlan->mode = nla_get_u32(data[IFLA_MACVLAN_MODE]);
if (vlan->mode == MACVLAN_MODE_PASSTHRU) {
- if (!list_empty(&port->vlans))
+ if (port->count)
return -EINVAL;
port->passthru = true;
memcpy(dev->dev_addr, lowerdev->dev_addr, ETH_ALEN);
}
+ port->count += 1;
err = register_netdevice(dev);
if (err < 0)
goto destroy_port;
@@ -707,7 +716,8 @@ int macvlan_common_newlink(struct net *src_net, struct net_device *dev,
return 0;
destroy_port:
- if (list_empty(&port->vlans))
+ port->count -= 1;
+ if (!port->count)
macvlan_port_destroy(lowerdev);
return err;
@@ -725,13 +735,9 @@ static int macvlan_newlink(struct net *src_net, struct net_device *dev,
void macvlan_dellink(struct net_device *dev, struct list_head *head)
{
struct macvlan_dev *vlan = netdev_priv(dev);
- struct macvlan_port *port = vlan->port;
list_del(&vlan->list);
unregister_netdevice_queue(dev, head);
-
- if (list_empty(&port->vlans))
- macvlan_port_destroy(port->dev);
}
EXPORT_SYMBOL_GPL(macvlan_dellink);
--
1.7.4
--
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