From e44201e4737d5bd9993f95482743c46dfdc3ed12 Mon Sep 17 00:00:00 2001 From: Petr Machata Date: Thu, 14 Feb 2019 13:44:11 +0800 Subject: [PATCH] vxlan: Fix error path in __vxlan_dev_create() mainline inclusion from mainline-4.20 commit 6db924687139 category: bugfix bugzilla: 6186 CVE: NA ------------------------------------------------- When a failure occurs in rtnl_configure_link(), the current code calls unregister_netdevice() to roll back the earlier call to register_netdevice(), and jumps to errout, which calls vxlan_fdb_destroy(). However unregister_netdevice() calls transitively ndo_uninit, which is vxlan_uninit(), and that already takes care of deleting the default FDB entry by calling vxlan_fdb_delete_default(). Since the entry added earlier in __vxlan_dev_create() is exactly the default entry, the cleanup code in the errout block always leads to double free and thus a panic. Besides, since vxlan_fdb_delete_default() always destroys the FDB entry with notification enabled, the deletion of the default entry is notified even before the addition was notified. Instead, move the unregister_netdevice() call after the manual destroy, which solves both problems. Fixes: 0241b836732f ("vxlan: fix default fdb entry netlink notify ordering during netdev create") Signed-off-by: Petr Machata Signed-off-by: David S. Miller Signed-off-by: Mao Wenan Reviewed-by: Wei Yongjun Signed-off-by: Yang Yingliang --- drivers/net/vxlan.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 27bd586b94b0..720c77071fbf 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -3190,6 +3190,7 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev, struct vxlan_net *vn = net_generic(net, vxlan_net_id); struct vxlan_dev *vxlan = netdev_priv(dev); struct vxlan_fdb *f = NULL; + bool unregister = false; int err; err = vxlan_dev_configure(net, dev, conf, false, extack); @@ -3215,12 +3216,11 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev, err = register_netdevice(dev); if (err) goto errout; + unregister = true; err = rtnl_configure_link(dev, NULL); - if (err) { - unregister_netdevice(dev); + if (err) goto errout; - } /* notify default fdb entry */ if (f) @@ -3228,9 +3228,16 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev, list_add(&vxlan->next, &vn->vxlan_list); return 0; + errout: + /* unregister_netdevice() destroys the default FDB entry with deletion + * notification. But the addition notification was not sent yet, so + * destroy the entry by hand here. + */ if (f) vxlan_fdb_destroy(vxlan, f, false); + if (unregister) + unregister_netdevice(dev); return err; } -- GitLab