Re: [PATCH net] dccp: call inet_add_protocol after register_pernet_subsys in dccp_v4_init

From: Xin Long <lucien.xin@gmail.com>
Date: Tue, 20 Jun 2017 15:42:38 +0800

Now dccp_ipv4 works as a kernel module. During loading this module, if
one dccp packet is being recieved after inet_add_protocol but before
register_pernet_subsys in which v4_ctl_sk is initialized, a null pointer
dereference may be triggered because of init_net.dccp.v4_ctl_sk is 0x0.

Jianlin found this issue when the following call trace occurred:

 ...

This patch is to move inet_add_protocol after register_pernet_subsys in
dccp_v4_init, so that v4_ctl_sk is initialized before any incoming dccp
packets are processed.

Reported-by: Jianlin Shi <redacted>
Signed-off-by: Xin Long <lucien.xin@gmail.com>

Applied.