ip6_gre: fix tunnel list corruption for x-netns

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 <[email protected]>
Signed-off-by: Olivier Matz <[email protected]>
Acked-by: Nicolas Dichtel <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 09d0826742f89f32fec444993f50812bbaec8366..f2543df50035e8d9b75520fb48dc4a0affd331b2 100644 (file)
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -2025,9 +2025,9 @@ static int ip6gre_changelink(struct net_device *dev, struct nlattr *tb[],
                             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))