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Subject[46/55] gre: fix netns vs proto registration ordering
2.6.32-longterm review patch.  If anyone has any objections, please let us know.

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

From: Alexey Dobriyan <adobriyan@gmail.com>

commit c2892f02712e9516d72841d5c019ed6916329794 upstream.

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>
[dannf: backported to Debian's 2.6.32]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/ipv4/ip_gre.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -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_gen_device(&ipgre_net_id, &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)
@@ -1688,9 +1689,9 @@ out:
tap_ops_failed:
rtnl_link_unregister(&ipgre_link_ops);
rtnl_link_failed:
- unregister_pernet_gen_device(ipgre_net_id, &ipgre_net_ops);
-gen_device_failed:
inet_del_protocol(&ipgre_protocol, IPPROTO_GRE);
+add_proto_failed:
+ unregister_pernet_gen_device(ipgre_net_id, &ipgre_net_ops);
goto out;
}

@@ -1698,9 +1699,9 @@ static void __exit ipgre_fini(void)
{
rtnl_link_unregister(&ipgre_tap_ops);
rtnl_link_unregister(&ipgre_link_ops);
- unregister_pernet_gen_device(ipgre_net_id, &ipgre_net_ops);
if (inet_del_protocol(&ipgre_protocol, IPPROTO_GRE) < 0)
printk(KERN_INFO "ipgre close: can't remove protocol\n");
+ unregister_pernet_gen_device(ipgre_net_id, &ipgre_net_ops);
}

module_init(ipgre_init);



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