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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Petr Machata <petrm@mellanox.com>,
        Olivier Matz <olivier.matz@6wind.com>,
        Nicolas Dichtel <nicolas.dichtel@6wind.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.19 017/103] ip6_gre: fix tunnel list corruption for x-netns
Date:   Tue, 29 Jan 2019 12:34:54 +0100
Message-Id: <20190129113200.562328418@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

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

From: Olivier Matz <olivier.matz@6wind.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@mellanox.com>
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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
@@ -2047,9 +2047,9 @@ 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))