From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Wed, 1 Nov 2017 10:23:49 -0700
Subject: net_sched: acquire RTNL in tc_action_net_exit()
Patch-mainline: v4.14-rc8
Git-commit: a159d3c4b8291998c018f0dbddd4678315264a1e
References: bsc#1109837

I forgot to acquire RTNL in tc_action_net_exit()
which leads that action ops->cleanup() is not always
called with RTNL. This usually is not a big deal because
this function is called after all netns refcnt are gone,
but given RTNL protects more than just actions, add it
for safety and consistency.

Also add an assertion to catch other potential bugs.

Fixes: ddf97ccdd7cb ("net_sched: add network namespace support for tc actions")
Reported-by: Lucas Bates <lucasb@mojatatu.com>
Tested-by: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/net/act_api.h |    2 ++
 net/sched/act_api.c   |    2 ++
 2 files changed, 4 insertions(+)

--- a/include/net/act_api.h
+++ b/include/net/act_api.h
@@ -122,7 +122,9 @@ void tcf_idrinfo_destroy(const struct tc
 
 static inline void tc_action_net_exit(struct tc_action_net *tn)
 {
+	rtnl_lock();
 	tcf_idrinfo_destroy(tn->ops, tn->idrinfo);
+	rtnl_unlock();
 	kfree(tn->idrinfo);
 }
 
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -86,6 +86,8 @@ int __tcf_idr_release(struct tc_action *
 {
 	int ret = 0;
 
+	ASSERT_RTNL();
+
 	if (p) {
 		if (bind)
 			p->tcfa_bindcnt--;