From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Mon, 6 Nov 2017 13:47:26 -0800
Subject: cls_matchall: use tcf_exts_get_net() before call_rcu()
Patch-mainline: v4.14
Git-commit: 57767e785321a427b8cdd282db2b8b33cd218ffa
References: bsc#1109837

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Cc: 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>
---
 net/sched/cls_matchall.c |   15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

--- a/net/sched/cls_matchall.c
+++ b/net/sched/cls_matchall.c
@@ -44,13 +44,19 @@ static int mall_init(struct tcf_proto *t
 	return 0;
 }
 
+static void __mall_destroy(struct cls_mall_head *head)
+{
+	tcf_exts_destroy(&head->exts);
+	tcf_exts_put_net(&head->exts);
+	kfree(head);
+}
+
 static void mall_destroy_work(struct work_struct *work)
 {
 	struct cls_mall_head *head = container_of(work, struct cls_mall_head,
 						  work);
 	rtnl_lock();
-	tcf_exts_destroy(&head->exts);
-	kfree(head);
+	__mall_destroy(head);
 	rtnl_unlock();
 }
 
@@ -109,7 +115,10 @@ static void mall_destroy(struct tcf_prot
 	if (tc_should_offload(dev, head->flags))
 		mall_destroy_hw_filter(tp, head, (unsigned long) head);
 
-	call_rcu(&head->rcu, mall_destroy_rcu);
+	if (tcf_exts_get_net(&head->exts))
+		call_rcu(&head->rcu, mall_destroy_rcu);
+	else
+		__mall_destroy(head);
 }
 
 static void *mall_get(struct tcf_proto *tp, u32 handle)