sit: More backports

At Red Hat we base our real-time kernel off of 3.10.27 and do lots of stress testing on that kernel. This has discovered some bugs that we can hit with the vanilla 3.10.27 kernel (no -rt patches applied).

I sent out a bug fix that can cause a crash with the current 3.10.27 when you add and then remove the sit module. That patch is obsoleted by these patches, as that patch was not enough.

A previous patch that was backported:

Upstream commit 205983c43700ac3a81e7625273a3fa83cd2759b5
sit: allow to use rtnl ops on fb tunnel

Had a depenency on commit 5e6700b3bf98 ("sit: add support of x-netns") which was not backported. The dependency was only on part of that commit which is what I backported.

The other upstream commit 9434266f2c645d4fcf62a03a8e36ad8075e37943
sit: fix use after free of fb_tunnel_dev

fixes another bug we encountered, it also fixes the 3.10.27 bug where removing the sit module cause the crash. This is the patch that obsoletes my previous patch.

-- Steve

Steven Rostedt (Red Hat) (1):
sit: Unregister sit devices with rtnl_link_ops

Willem de Bruijn (1):
sit: fix use after free of fb_tunnel_dev

----

 net/ipv6/sit.c | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

From: "Steven Rostedt (Red Hat)" <[email protected]>

The backport of upstream commit 205983c43700ac3 ("sit: allow to use rtnl ops on fb tunnel") had a dependency on commit 5e6700b3bf98 ("sit: add support of x-netns"). The dependency was on the way that commit unregistered the sit devices.

Since the entire commit 5e6700b3bf98 is not necessary for a backport we only need to backport the part required for the backport of 205983c43700ac3. This is the loop to unregister the sit devices where dev->rtnl_link_ops == &sit_link_ops.

---
 net/ipv6/sit.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

index 0491264..3652033 100644
@@ -1529,6 +1529,10 @@ static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_hea
 {
 	int prio;
 
+	for_each_netdev_safe(net, dev, aux)
+		if (dev->rtnl_link_ops == &sit_link_ops)
+			unregister_netdevice_queue(dev, head);
+
 	for (prio = 1; prio < 4; prio++) {
 		int h;
 		for (h = 0; h < HASH_SIZE; h++) {

@@ -1536,7 +1540,12 @@ static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_hea
 
 			t = rtnl_dereference(sitn->tunnels[prio][h]);
 			while (t != NULL) {
-				unregister_netdevice_queue(t->dev, head);
+				/* If dev is in the same netns, it has already
+				 * been added to the list by the previous loop.
+				 */
+				if (dev_net(t->dev) != net)
+					unregister_netdevice_queue(t->dev,
+								   head);
 				t = rtnl_dereference(t->next);
 			}
 		}

1.8.4.3

From: Willem de Bruijn <[email protected]>

[ Upstream commit 9434266f2c645d4fcf62a03a8e36ad8075e37943 ]

Bug: The fallback device is created in sit_init_net and assumed to be freed in sit_exit_net. First, it is dereferenced in that function, in sit_destroy_tunnels:

        struct net *net = dev_net(sitn->fb_tunnel_dev);

Prior to this, rtnl_unlink_register has removed all devices that match rtnl_link_ops == sit_link_ops.

Commit 205983c43700 added the line

+ sitn->fb_tunnel_dev->rtnl_link_ops = &sit_link_ops;

which cases the fallback device to match here and be freed before it is last dereferenced.

Fix: This commit adds an explicit .delllink callback to sit_link_ops that skips deallocation at rtnl_unlink_register for the fallback device. This mechanism is comparable to the one in ip_tunnel.

It also modifies sit_destroy_tunnels and its only caller sit_exit_net to avoid the offending dereference in the first place. That double lookup is more complicated than required.

Test: The bug is only triggered when CONFIG_NET_NS is enabled. It causes a GPF only when CONFIG_DEBUG_SLAB is enabled. Verified that this bug exists at the mentioned commit, at davem-net HEAD and at 3.11.y HEAD. Verified that it went away after applying this patch.

---
 net/ipv6/sit.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

index 3652033..d80055a 100644
@@ -1507,6 +1507,15 @@ static const struct nla_policy ipip6_policy[IFLA_IPTUN_MAX + 1] = {
 #endif
 };
 
+static void ipip6_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct net *net = dev_net(dev);
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+
+	if (dev != sitn->fb_tunnel_dev)
+		unregister_netdevice_queue(dev, head);
+}
+
 static struct rtnl_link_ops sit_link_ops __read_mostly = {
 	.kind		= "sit",
 	.maxtype	= IFLA_IPTUN_MAX,

@@ -1517,6 +1526,7 @@ static struct rtnl_link_ops sit_link_ops __read_mostly = {
 	.changelink	= ipip6_changelink,
 	.get_size	= ipip6_get_size,
 	.fill_info	= ipip6_fill_info,
+	.dellink	= ipip6_dellink,
 };
 
 static struct xfrm_tunnel sit_handler __read_mostly = {

@@ -1525,8 +1535,11 @@ static struct xfrm_tunnel sit_handler __read_mostly = {
 	.priority	=	1,
 };
 
-static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_head *head)
+static void __net_exit sit_destroy_tunnels(struct net *net,
+					   struct list_head *head)
 {
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+	struct net_device *dev, *aux;
 	int prio;
 
 	for_each_netdev_safe(net, dev, aux)

@@ -1596,12 +1609,10 @@ err_alloc_dev:
 
 static void __net_exit sit_exit_net(struct net *net)
 {
-	struct sit_net *sitn = net_generic(net, sit_net_id);
 	LIST_HEAD(list);
 
 	rtnl_lock();
-	sit_destroy_tunnels(sitn, &list);
-	unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);
+	sit_destroy_tunnels(net, &list);
 	unregister_netdevice_many(&list);
 	rtnl_unlock();
 }

1.8.4.3

From: Steven Rostedt <[email protected]>
Date: Tue, 28 Jan 2014 15:57:56 -0500

Greg, these have my blessing, please apply these to 3.10 -stable, thanks a lot!

Hi David,

Thanks for the blessing :-) But I want to work with Nicolas a bit more to make sure that I have a correct backport. Just because it fixed some of our bugs doesn't mean that I didn't make new ones.

Thanks,

-- Steve

Can you explain a bit more which problem remains after that patch? I wonder if a problem remains also with ip6_tunnel.ko (net/ipv6/ip6_tunnel.c), the same problem was spotted into this module.

I cannot comment directly the patch, it was an attachement, hence I put my comments here.
In patch 0001-sit-Unregister-sit-devices-with-rtnl_link_ops.patch, I wonder how 'if (dev_net(t->dev) != net)' can be wrong. If commit 5e6700b3bf98 ("sit: add support of x-netns") has not been backported, this test is always true.

Hmm, OK it may only need the first version of the patch. It was one of those cases where it didn't fix the second bug, so we added the full patch as well. Then we found the second bug but never tried all the tests with the smaller version of the patch. I'll put back the first patch and then ask our QA to retest it with the older version and the other patch.

It's not really an attachment. It was sent with quilt mail, which only makes it look like one. What mail client are you using? mutt, alpine, evolution, claws-mail, and thunderbird all show it as a normal patch. I do know that k9-mail on android makes it into an attachment.

Should it just be removed then? This has fixed our bugs, but perhaps it opened new ones we haven't detected yet. I can remove the if and unregister and see if it still works. Or perhaps calling unregister all the time isn't bad.

-- Steve

Thunderbird. The patch was show as a normal aptch, but when I do "reply all", I get an empty mail.

Ok, I've think a bit more to this problem. First, let's explain it.

rmmod sit
=> sit_cleanup()
=> rtnl_link_unregister()

    => __rtnl_kill_links()
      => for_each_netdev(net, dev) {
           if (dev->rtnl_link_ops == ops)
              ops->dellink(dev, &list_kill);
         }

**at this point, the FB device is deleted (and all sit tunnels)**

=> unregister_pernet_device()

    => unregister_pernet_operations()
      => ops_exit_list()
        => sit_exit_net()
          => sit_destroy_tunnels()
             in this function, no tunnel is found
          unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);

** second deletion, here is the bug **

Now, what happen on netns deletion with the previous patch? Only sit_exit_net() will be called, hence with the previous patch, the fb device will not be destroyed, netns will leak.

Your patch serie seems to be the good way to go (note that patch 1/2 does not compile) but I think the fix is smaller because we don't have x-netns.

Here is my proposal, if you agree, I will send the same patch for ip6_tunnnel, which have the netns leak.

From d101450583c3a472a2a94904cfe13fd4e7d2f519 Mon Sep 17 00:00:00 2001
From: Nicolas Dichtel <[email protected]>
Date: Wed, 29 Jan 2014 16:40:30 +0100
Subject: [PATCH] sit: fix double free of fb_tunnel_dev on exit

This problem was fixed upstream by commit 9434266f2c64 ("sit: fix use after free of fb_tunnel_dev").
The upstream patch depends on upstream commit 5e6700b3bf98 ("sit: add support of x-netns"), which was not backported into 3.10 branch.

First, explain the problem: when the sit module is unloaded, sit_cleanup() is called.
rmmod sit
=> sit_cleanup()
=> rtnl_link_unregister()

    => __rtnl_kill_links()
      => for_each_netdev(net, dev) {
        if (dev->rtnl_link_ops == ops)
        	ops->dellink(dev, &list_kill);
        }
At this point, the FB device is deleted (and all sit tunnels).
  => unregister_pernet_device()
    => unregister_pernet_operations()
      => ops_exit_list()
        => sit_exit_net()
          => sit_destroy_tunnels()
          In this function, no tunnel is found.
          => unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);

We delete the FB device a second time here!

Because we cannot simply remove the second deletion (sit_exit_net() must remove the FB device when a netns is deleted), we add an rtnl ops which delete all sit device excepting the FB device and thus we can keep the explicit deletion in sit_exit_net().

---
 net/ipv6/sit.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

index 0491264b8bfc..620d326e8fdd 100644
@@ -1507,6 +1507,15 @@ static const struct nla_policy ipip6_policy[IFLA_IPTUN_MAX + 1] = {
 #endif
 };
 
+static void ipip6_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct net *net = dev_net(dev);
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+
+	if (dev != sitn->fb_tunnel_dev)
+		unregister_netdevice_queue(dev, head);
+}
+
 static struct rtnl_link_ops sit_link_ops __read_mostly = {
 	.kind		= "sit",
 	.maxtype	= IFLA_IPTUN_MAX,

@@ -1517,6 +1526,7 @@ static struct rtnl_link_ops sit_link_ops __read_mostly = {
 	.changelink	= ipip6_changelink,
 	.get_size	= ipip6_get_size,
 	.fill_info	= ipip6_fill_info,
+	.dellink	= ipip6_dellink,
 };
 
 static struct xfrm_tunnel sit_handler __read_mostly = {

1.8.4.1

This looks good to me. It is the same as the backport "sit: fix use after free of fb_tunnel_dev" (9434266f2c64), minus the small code cleanup at the end of that patch that is not relevant to 3.10.27 (do not define sit_net *sitn in sit_exit_net if it is not used there. But in 3.10.27 it is used, in unregister_netdevice_queue).

Hold on. Seems that the kernels that were being tested in QA had more code than what I was testing. Clark had backported "sit: fix use after free of fb_tunnel_dev" and that was what was causing the unlist_netdevice() to be missed.

When I started working on vanilla 3.10.27 as well, I first did my original patch (which just removes the call to unregister_netdevice_queue() from sit_exit_net()). I asked to have that added to our kernel for testing, and they told me it was already there via Clark's backport. Then I did the full backport as well and looked for the leak. I'm now thinking that the full backport is not needed as that was what caused the leak.

According to commit 9434266f2c645d4fcf62a03a8e36ad8075e37943 "sit: fix use after free of fb_tunnel_dev", it states:

Bug: The fallback device is created in sit_init_net and assumed to be freed in sit_exit_net. First, it is dereferenced in that function, in sit_destroy_tunnels:

struct net *net = dev_net(sitn->fb_tunnel_dev);

Prior to this, rtnl_unlink_register has removed all devices that match rtnl_link_ops == sit_link_ops.

Commit 205983c43700 added the line

+ sitn->fb_tunnel_dev->rtnl_link_ops = &sit_link_ops;

which cases the fallback device to match here and be freed before it is last dereferenced.

Commit 205983c43700 was backported to 3.10, but without commit 5e6700b3bf98 "sit: add support of x-netns" which was what added the

  net = dev_net(sitn->fb_tunnel_dev);

Which looks to me that the only reason I need to port back commit 5e6700b3bf98 is if I add the full backport of 9434266f2c645d4f.

Seems to me that my original patch may be good enough. The one that I said this series obsoletes.

Note, I've talked with the people that are doing the testing, and I'm having them revert all changes except for that one fix and rerun the tests again. I should know the results by tomorrow.

Let me know if "sit: fix use after free of fb_tunnel_dev" still needs to be backported due to some other way that the fallback device can be dereferenced after being freed.

-- Steve

Steve, I think the patch I sent yesterday is the good fix. At the end, it's a backport of Willem's patch. Note that he also ack that patch. The first version you sent (which removes unregister_netdevice_queue(sitn->fb_tunnel_dev, &list)) will introduce a memory leak when the user destroy a netns.

This problem was fixed upstream by commit 9434266f2c64 ("sit: fix use after free of fb_tunnel_dev").
The upstream patch depends on upstream commit 5e6700b3bf98 ("sit: add support of x-netns"), which was not backported into 3.10 branch.

First, explain the problem: when the sit module is unloaded, sit_cleanup() is called.
rmmod sit
=> sit_cleanup()
=> rtnl_link_unregister()

    => __rtnl_kill_links()
      => for_each_netdev(net, dev) {
        if (dev->rtnl_link_ops == ops)
        	ops->dellink(dev, &list_kill);
        }
At this point, the FB device is deleted (and all sit tunnels).
  => unregister_pernet_device()
    => unregister_pernet_operations()
      => ops_exit_list()
        => sit_exit_net()
          => sit_destroy_tunnels()
          In this function, no tunnel is found.
          => unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);

We delete the FB device a second time here!

Because we cannot simply remove the second deletion (sit_exit_net() must remove the FB device when a netns is deleted), we add an rtnl ops which delete all sit device excepting the FB device and thus we can keep the explicit deletion in sit_exit_net().

---
 net/ipv6/sit.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

index 0491264b8bfc..620d326e8fdd 100644
@@ -1507,6 +1507,15 @@ static const struct nla_policy ipip6_policy[IFLA_IPTUN_MAX + 1] = {
 #endif
 };
 
+static void ipip6_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct net *net = dev_net(dev);
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+
+	if (dev != sitn->fb_tunnel_dev)
+		unregister_netdevice_queue(dev, head);
+}
+
 static struct rtnl_link_ops sit_link_ops __read_mostly = {
 	.kind		= "sit",
 	.maxtype	= IFLA_IPTUN_MAX,

@@ -1517,6 +1526,7 @@ static struct rtnl_link_ops sit_link_ops __read_mostly = {
 	.changelink	= ipip6_changelink,
 	.get_size	= ipip6_get_size,
 	.fill_info	= ipip6_fill_info,
+	.dellink	= ipip6_dellink,
 };
 
 static struct xfrm_tunnel sit_handler __read_mostly = {

1.8.4.1

This reverts commit 22c3ec552c29cf4bd4a75566088950fe57d860c4.

This patch is not the right fix, it introduces a memory leak when a netns is destroyed (the FB device is never deleted).

---
 net/ipv6/ip6_tunnel.c | 2 ++
 1 file changed, 2 insertions(+)

index 209bb4d6e188..0516ebbea80b 100644
@@ -1711,6 +1711,8 @@ static void __net_exit ip6_tnl_destroy_tunnels(struct ip6_tnl_net *ip6n)
 		}
 	}
 
+	t = rtnl_dereference(ip6n->tnls_wc[0]);
+	unregister_netdevice_queue(t->dev, &list);
 	unregister_netdevice_many(&list);
 }
 

1.8.4.1

This problem was fixed upstream by commit 1e9f3d6f1c40 ("ip6tnl: fix use after free of fb_tnl_dev").
The upstream patch depends on upstream commit 0bd8762824e7 ("ip6tnl: add x-netns support"), which was not backported into 3.10 branch.

First, explain the problem: when the ip6_tunnel module is unloaded, ip6_tunnel_cleanup() is called.
rmmod ip6_tunnel
=> ip6_tunnel_cleanup()
=> rtnl_link_unregister()

    => __rtnl_kill_links()
      => for_each_netdev(net, dev) {
        if (dev->rtnl_link_ops == ops)
        	ops->dellink(dev, &list_kill);
        }
At this point, the FB device is deleted (and all ip6tnl tunnels).
  => unregister_pernet_device()
    => unregister_pernet_operations()
      => ops_exit_list()
        => ip6_tnl_exit_net()
          => ip6_tnl_destroy_tunnels()
            => t = rtnl_dereference(ip6n->tnls_wc[0]);
               unregister_netdevice_queue(t->dev, &list);

We delete the FB device a second time here!

The previous fix removes these lines, which fix this double free. But the patch introduces a memory leak when a netns is destroyed, because the FB device is never deleted. By adding an rtnl ops which delete all ip6tnl device excepting the FB device, we can keep this exlicit removal in ip6_tnl_destroy_tunnels().

---
 net/ipv6/ip6_tunnel.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

index 0516ebbea80b..f21cf476b00c 100644
@@ -1617,6 +1617,15 @@ static int ip6_tnl_changelink(struct net_device *dev, struct nlattr *tb[],
 	return ip6_tnl_update(t, &p);
 }
 
+static void ip6_tnl_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct net *net = dev_net(dev);
+	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
+
+	if (dev != ip6n->fb_tnl_dev)
+		unregister_netdevice_queue(dev, head);
+}
+
 static size_t ip6_tnl_get_size(const struct net_device *dev)
 {
 	return

@@ -1681,6 +1690,7 @@ static struct rtnl_link_ops ip6_link_ops __read_mostly = {
 	.validate	= ip6_tnl_validate,
 	.newlink	= ip6_tnl_newlink,
 	.changelink	= ip6_tnl_changelink,
+	.dellink	= ip6_tnl_dellink,
 	.get_size	= ip6_tnl_get_size,
 	.fill_info	= ip6_tnl_fill_info,
 };

1.8.4.1

Hi Nicolas,

I reverted my patches and applied and tested your patches locally and they passed my first line testing. I'm going to have them entered into our test suite, after removing our other patches, and see if they solve all the bugs that we were tripping over.

I'll let you know when these are finished.

Thanks!

-- Steve

Thank you for testing.

Regards,
Nicolas

Our short tests that were crashing have all now passed :-) with your patches applied.

We are now running our full tier tests on the code, but I don't think we need to wait. Please add my tags to your patches, and hopefully we can get David to give us a new blessing on your patch set.

David and Greg,

You can ignore my patches as it seems that Nicolas's patches solve the issues we have been seeing on 3.10.

Nicolas,

Thanks for all your effort in helping us out here :-)

I don't usually give my Red Hat email for things like this, but as this was found and tested with the Red Hat infrastructure, with the help from Luis and John (and others), I would like to give them credit too.

-- Steve

This problem was fixed upstream by commit 9434266f2c64 ("sit: fix use after free of fb_tunnel_dev").
The upstream patch depends on upstream commit 5e6700b3bf98 ("sit: add support of x-netns"), which was not backported into 3.10 branch.

First, explain the problem: when the sit module is unloaded, sit_cleanup() is called.
rmmod sit
=> sit_cleanup()
=> rtnl_link_unregister()

    => __rtnl_kill_links()
      => for_each_netdev(net, dev) {
        if (dev->rtnl_link_ops == ops)
        	ops->dellink(dev, &list_kill);
        }
At this point, the FB device is deleted (and all sit tunnels).
  => unregister_pernet_device()
    => unregister_pernet_operations()
      => ops_exit_list()
        => sit_exit_net()
          => sit_destroy_tunnels()
          In this function, no tunnel is found.
          => unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);

We delete the FB device a second time here!

Because we cannot simply remove the second deletion (sit_exit_net() must remove the FB device when a netns is deleted), we add an rtnl ops which delete all sit device excepting the FB device and thus we can keep the explicit deletion in sit_exit_net().

---

v2: add Steven's tags

 net/ipv6/sit.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

index 0491264b8bfc..620d326e8fdd 100644
@@ -1507,6 +1507,15 @@ static const struct nla_policy ipip6_policy[IFLA_IPTUN_MAX + 1] = {
 #endif
 };
 
+static void ipip6_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct net *net = dev_net(dev);
+	struct sit_net *sitn = net_generic(net, sit_net_id);
+
+	if (dev != sitn->fb_tunnel_dev)
+		unregister_netdevice_queue(dev, head);
+}
+
 static struct rtnl_link_ops sit_link_ops __read_mostly = {
 	.kind		= "sit",
 	.maxtype	= IFLA_IPTUN_MAX,

@@ -1517,6 +1526,7 @@ static struct rtnl_link_ops sit_link_ops __read_mostly = {
 	.changelink	= ipip6_changelink,
 	.get_size	= ipip6_get_size,
 	.fill_info	= ipip6_fill_info,
+	.dellink	= ipip6_dellink,
 };
 
 static struct xfrm_tunnel sit_handler __read_mostly = {

1.8.4.1

This reverts commit 22c3ec552c29cf4bd4a75566088950fe57d860c4.

This patch is not the right fix, it introduces a memory leak when a netns is destroyed (the FB device is never deleted).

---

v2: add Steven's tags

 net/ipv6/ip6_tunnel.c | 2 ++
 1 file changed, 2 insertions(+)

index 209bb4d6e188..0516ebbea80b 100644
@@ -1711,6 +1711,8 @@ static void __net_exit ip6_tnl_destroy_tunnels(struct ip6_tnl_net *ip6n)
 		}
 	}
 
+	t = rtnl_dereference(ip6n->tnls_wc[0]);
+	unregister_netdevice_queue(t->dev, &list);
 	unregister_netdevice_many(&list);
 }
 

1.8.4.1

This problem was fixed upstream by commit 1e9f3d6f1c40 ("ip6tnl: fix use after free of fb_tnl_dev").
The upstream patch depends on upstream commit 0bd8762824e7 ("ip6tnl: add x-netns support"), which was not backported into 3.10 branch.

First, explain the problem: when the ip6_tunnel module is unloaded, ip6_tunnel_cleanup() is called.
rmmod ip6_tunnel
=> ip6_tunnel_cleanup()
=> rtnl_link_unregister()

    => __rtnl_kill_links()
      => for_each_netdev(net, dev) {
        if (dev->rtnl_link_ops == ops)
        	ops->dellink(dev, &list_kill);
        }
At this point, the FB device is deleted (and all ip6tnl tunnels).
  => unregister_pernet_device()
    => unregister_pernet_operations()
      => ops_exit_list()
        => ip6_tnl_exit_net()
          => ip6_tnl_destroy_tunnels()
            => t = rtnl_dereference(ip6n->tnls_wc[0]);
               unregister_netdevice_queue(t->dev, &list);

We delete the FB device a second time here!

The previous fix removes these lines, which fix this double free. But the patch introduces a memory leak when a netns is destroyed, because the FB device is never deleted. By adding an rtnl ops which delete all ip6tnl device excepting the FB device, we can keep this exlicit removal in ip6_tnl_destroy_tunnels().

---

v2: add Steven's tags

 net/ipv6/ip6_tunnel.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

index 0516ebbea80b..f21cf476b00c 100644
@@ -1617,6 +1617,15 @@ static int ip6_tnl_changelink(struct net_device *dev, struct nlattr *tb[],
 	return ip6_tnl_update(t, &p);
 }
 
+static void ip6_tnl_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct net *net = dev_net(dev);
+	struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
+
+	if (dev != ip6n->fb_tnl_dev)
+		unregister_netdevice_queue(dev, head);
+}
+
 static size_t ip6_tnl_get_size(const struct net_device *dev)
 {
 	return

@@ -1681,6 +1690,7 @@ static struct rtnl_link_ops ip6_link_ops __read_mostly = {
 	.validate	= ip6_tnl_validate,
 	.newlink	= ip6_tnl_newlink,
 	.changelink	= ip6_tnl_changelink,
+	.dellink	= ip6_tnl_dellink,
 	.get_size	= ip6_tnl_get_size,
 	.fill_info	= ip6_tnl_fill_info,
 };

1.8.4.1

Just FYI.

Our full tier tests have completed with no issues due to the sit or ip6_tunnel modules. These patches appear to have solved our problems.

Nicolas, Thanks again for posting these!

-- Steve