net/net_namespace: Check the return value of register_pernet_subsys()

[ Upstream commit 0eb987c874dc93f9c9d85a6465dbde20fdd3884c ]

In net_ns_init(), register_pernet_subsys() could fail while registering
network namespace subsystems. The fix checks the return value and
sends a panic() on failure.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 4509dec..7630fa8 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -802,7 +802,8 @@
 
 	mutex_unlock(&net_mutex);
 
-	register_pernet_subsys(&net_ns_ops);
+	if (register_pernet_subsys(&net_ns_ops))
+		panic("Could not register network namespace subsystems");
 
 	rtnl_register(PF_UNSPEC, RTM_NEWNSID, rtnl_net_newid, NULL, NULL);
 	rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, rtnl_net_dumpid,