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gre: fix netns vs proto registration ordering
GRE protocol receive hook can be called right after protocol addition is done.
If netns stuff is not yet initialized, we're going to oops in
net_generic().

This is remotely oopsable if ip_gre is compiled as module and packet
comes at unfortunate moment of module loading.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Alexey Dobriyan authored and davem330 committed Feb 16, 2010
1 parent 749f621 commit c2892f0
Showing 1 changed file with 10 additions and 9 deletions.
19 changes: 10 additions & 9 deletions net/ipv4/ip_gre.c
Expand Up @@ -1665,14 +1665,15 @@ static int __init ipgre_init(void)

printk(KERN_INFO "GRE over IPv4 tunneling driver\n");

if (inet_add_protocol(&ipgre_protocol, IPPROTO_GRE) < 0) {
printk(KERN_INFO "ipgre init: can't add protocol\n");
return -EAGAIN;
}

err = register_pernet_device(&ipgre_net_ops);
if (err < 0)
goto gen_device_failed;
return err;

err = inet_add_protocol(&ipgre_protocol, IPPROTO_GRE);
if (err < 0) {
printk(KERN_INFO "ipgre init: can't add protocol\n");
goto add_proto_failed;
}

err = rtnl_link_register(&ipgre_link_ops);
if (err < 0)
Expand All @@ -1688,19 +1689,19 @@ static int __init ipgre_init(void)
tap_ops_failed:
rtnl_link_unregister(&ipgre_link_ops);
rtnl_link_failed:
unregister_pernet_device(&ipgre_net_ops);
gen_device_failed:
inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
add_proto_failed:
unregister_pernet_device(&ipgre_net_ops);
goto out;
}

static void __exit ipgre_fini(void)
{
rtnl_link_unregister(&ipgre_tap_ops);
rtnl_link_unregister(&ipgre_link_ops);
unregister_pernet_device(&ipgre_net_ops);
if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0)
printk(KERN_INFO "ipgre close: can't remove protocol\n");
unregister_pernet_device(&ipgre_net_ops);
}

module_init(ipgre_init);
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