From: Eric Dumazet <edumazet@google.com>
Date: Fri, 6 Jun 2014 13:44:03 +0000 (-0700)
Subject: net: force a list_del() in unregister_netdevice_many()
X-Git-Tag: v3.14.9~43
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0d0fc9f9e888a6e3fdabdfc08b7c4044b58bc87a;p=thirdparty%2Fkernel%2Fstable.git

net: force a list_del() in unregister_netdevice_many()

[ 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>
---

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 20bb66944c4a8..5adecc5f52b71 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -1043,7 +1043,6 @@ static int macvlan_device_event(struct notifier_block *unused,
 		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. */
diff --git a/net/core/dev.c b/net/core/dev.c
index fccc195e0fc8d..4c1b483f7c077 100644
--- 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 list_head *head)
 		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_exit_batch(struct list_head *net_list)
 		}
 	}
 	unregister_netdevice_many(&dev_kill_list);
-	list_del(&dev_kill_list);
 	rtnl_unlock();
 }
 
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 5cb7220e2abd3..473e7e908e38d 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1735,7 +1735,6 @@ static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh)
 
 	ops->dellink(dev, &list_kill);
 	unregister_netdevice_many(&list_kill);
-	list_del(&list_kill);
 	return 0;
 }
 
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index ce1c443706104..8f7fabc46c975 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1761,7 +1761,6 @@ void ieee80211_remove_interfaces(struct ieee80211_local *local)
 	}
 	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);