3.16.63-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Petr Machata petrm@mellanox.com
commit 6db9246871394b3a136cd52001a0763676563840 upstream.
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 petrm@mellanox.com Signed-off-by: David S. Miller davem@davemloft.net [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/net/vxlan.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
--- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -2615,6 +2615,7 @@ static int vxlan_newlink(struct net *net struct vxlan_dev *vxlan = netdev_priv(dev), *tmp; struct vxlan_rdst *dst = &vxlan->default_dst; struct vxlan_fdb *f = NULL; + bool unregister = false; __u32 vni; int err; bool use_ipv6 = false; @@ -2766,12 +2767,11 @@ static int vxlan_newlink(struct net *net 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) @@ -2780,9 +2780,16 @@ static int vxlan_newlink(struct net *net 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); + if (unregister) + unregister_netdevice(dev); return err; }