linux-kernel - [PATCH 4.20 017/117] ip6_gre: fix tunnel list corruption for x-netns

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Date:   Tue, 29 Jan 2019 12:34:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Petr Machata <petrm@...lanox.com>,
        Olivier Matz <olivier.matz@...nd.com>,
        Nicolas Dichtel <nicolas.dichtel@...nd.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.20 017/117] ip6_gre: fix tunnel list corruption for x-netns

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Olivier Matz <olivier.matz@...nd.com>

[ Upstream commit ab5098fa25b91cb6fe0a0676f17abb64f2bbf024 ]

In changelink ops, the ip6gre_net pointer is retrieved from
dev_net(dev), which is wrong in case of x-netns. Thus, the tunnel is not
unlinked from its current list and is relinked into another net
namespace. This corrupts the tunnel lists and can later trigger a kernel
oops.

Fix this by retrieving the netns from device private area.

Fixes: c8632fc30bb0 ("net: ip6_gre: Split up ip6gre_changelink()")
Cc: Petr Machata <petrm@...lanox.com>
Signed-off-by: Olivier Matz <olivier.matz@...nd.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv6/ip6_gre.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -2029,9 +2029,9 @@ static int ip6gre_changelink(struct net_
 			     struct nlattr *data[],
 			     struct netlink_ext_ack *extack)
 {
-	struct ip6gre_net *ign = net_generic(dev_net(dev), ip6gre_net_id);
+	struct ip6_tnl *t = netdev_priv(dev);
+	struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);
 	struct __ip6_tnl_parm p;
-	struct ip6_tnl *t;
 
 	t = ip6gre_changelink_common(dev, tb, data, &p, extack);
 	if (IS_ERR(t))