Patch "vxlan: fix use-after-free on deletion" has been added to the 4.4-stable tree

Patch "vxlan: fix use-after-free on deletion" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    vxlan: fix use-after-free on deletion

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     vxlan-fix-use-after-free-on-deletion.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Jun  8 09:11:25 CEST 2017
From: Mark Bloch <markb@mellanox.com>
Date: Fri, 2 Jun 2017 03:24:08 +0300
Subject: vxlan: fix use-after-free on deletion

From: Mark Bloch <markb@mellanox.com>


[ Upstream commit a53cb29b0af346af44e4abf13d7e59f807fba690 ]

Adding a vxlan interface to a socket isn't symmetrical, while adding
is done in vxlan_open() the deletion is done in vxlan_dellink().
This can cause a use-after-free error when we close the vxlan
interface before deleting it.

We add vxlan_vs_del_dev() to match vxlan_vs_add_dev() and call
it from vxlan_stop() to match the call from vxlan_open().

Fixes: 56ef9c909b40 ("vxlan: Move socket initialization to within rtnl scope")
Acked-by: Jiri Benc <jbenc@redhat.com>
Tested-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Mark Bloch <markb@mellanox.com>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/vxlan.c |   19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -77,6 +77,8 @@ static const u8 all_zeros_mac[ETH_ALEN];
 
 static int vxlan_sock_add(struct vxlan_dev *vxlan);
 
+static void vxlan_vs_del_dev(struct vxlan_dev *vxlan);
+
 /* per-network namespace private data for this module */
 struct vxlan_net {
 	struct list_head  vxlan_list;
@@ -1052,6 +1054,8 @@ static void __vxlan_sock_release(struct
 
 static void vxlan_sock_release(struct vxlan_dev *vxlan)
 {
+	vxlan_vs_del_dev(vxlan);
+
 	__vxlan_sock_release(vxlan->vn4_sock);
 #if IS_ENABLED(CONFIG_IPV6)
 	__vxlan_sock_release(vxlan->vn6_sock);
@@ -2255,6 +2259,15 @@ static void vxlan_cleanup(unsigned long
 	mod_timer(&vxlan->age_timer, next_timer);
 }
 
+static void vxlan_vs_del_dev(struct vxlan_dev *vxlan)
+{
+	struct vxlan_net *vn = net_generic(vxlan->net, vxlan_net_id);
+
+	spin_lock(&vn->sock_lock);
+	hlist_del_init_rcu(&vxlan->hlist);
+	spin_unlock(&vn->sock_lock);
+}
+
 static void vxlan_vs_add_dev(struct vxlan_sock *vs, struct vxlan_dev *vxlan)
 {
 	struct vxlan_net *vn = net_generic(vxlan->net, vxlan_net_id);
@@ -3028,12 +3041,6 @@ static int vxlan_newlink(struct net *src
 static void vxlan_dellink(struct net_device *dev, struct list_head *head)
 {
 	struct vxlan_dev *vxlan = netdev_priv(dev);
-	struct vxlan_net *vn = net_generic(vxlan->net, vxlan_net_id);
-
-	spin_lock(&vn->sock_lock);
-	if (!hlist_unhashed(&vxlan->hlist))
-		hlist_del_rcu(&vxlan->hlist);
-	spin_unlock(&vn->sock_lock);
 
 	gro_cells_destroy(&vxlan->gro_cells);
 	list_del(&vxlan->next);


Patches currently in stable-queue which might be from markb@mellanox.com are

queue-4.4/vxlan-fix-use-after-free-on-deletion.patch