[PATCH 3.14 26/68] net: force a list_del() in unregister_netdevice_many()

Greg Kroah-Hartman
2014-06-24T16:26:33Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 87757a917b0b3c0787e0563c679762152be81312 ]

unregister_netdevice_many() API is error prone and we had too
many bugs because of dangling LIST_HEAD on stacks.

See commit f87e6f47933e3e ("net: dont leave active on stack LIST_HEAD")

In fact, instead of making sure no caller leaves an active list_head,
just force a list_del() in the callee. No one seems to need to access
the list after unregister_netdevice_many()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/macvlan.c | 1 -
net/core/dev.c | 5 ++++-
net/core/rtnetlink.c | 1 -
net/mac80211/iface.c | 1 -
4 files changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -1043,7 +1043,6 @@ static int macvlan_device_event(struct n
list_for_each_entry_safe(vlan, next, &port->vlans, list)
vlan->dev->rtnl_link_ops->dellink(vlan->dev, &list_kill);
unregister_netdevice_many(&list_kill);
- list_del(&list_kill);
break;
case NETDEV_PRE_TYPE_CHANGE:
/* Forbid underlaying device to change its type. */
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6548,6 +6548,9 @@ EXPORT_SYMBOL(unregister_netdevice_queue
/**
* unregister_netdevice_many - unregister many devices
* @head: list of devices
+ *
+ * Note: As most callers use a stack allocated list_head,
+ * we force a list_del() to make sure stack wont be corrupted later.
*/
void unregister_netdevice_many(struct list_head *head)
{
@@ -6557,6 +6560,7 @@ void unregister_netdevice_many(struct li
rollback_registered_many(head);
list_for_each_entry(dev, head, unreg_list)
net_set_todo(dev);
+ list_del(head);
}
}
EXPORT_SYMBOL(unregister_netdevice_many);
@@ -7012,7 +7016,6 @@ static void __net_exit default_device_ex
}
}
unregister_netdevice_many(&dev_kill_list);
- list_del(&dev_kill_list);
rtnl_unlock();
}

--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1735,7 +1735,6 @@ static int rtnl_dellink(struct sk_buff *

ops->dellink(dev, &list_kill);
unregister_netdevice_many(&list_kill);
- list_del(&list_kill);
return 0;
}

--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1761,7 +1761,6 @@ void ieee80211_remove_interfaces(struct
}
mutex_unlock(&local->iflist_mtx);
unregister_netdevice_many(&unreg_list);
- list_del(&unreg_list);

list_for_each_entry_safe(sdata, tmp, &wdev_list, list) {
list_del(&sdata->list);