netdev - [patch net] net: sched: fix memleak for chain zero

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Date:   Wed,  6 Sep 2017 13:14:19 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, jhs@...atatu.com, xiyou.wangcong@...il.com,
        kubakici@...pl, mlxsw@...lanox.com
Subject: [patch net] net: sched: fix memleak for chain zero

From: Jiri Pirko <jiri@...lanox.com>

There's a memleak happening for chain 0. The thing is, chain 0 needs to
be always present, not created on demand. Therefore tcf_block_get upon
creation of block calls the tcf_chain_create function directly. The
chain is created with refcnt == 1, which is not correct in this case and
causes the memleak. So move the refcnt increment into tcf_chain_get
function even for the case when chain needs to be created.

Reported-by: Jakub Kicinski <kubakici@...pl>
Fixes: 5bc1701881e3 ("net: sched: introduce multichain support for filters")
Signed-off-by: Jiri Pirko <jiri@...lanox.com>
---
 net/sched/cls_api.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 6c5ea84..30ef466 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -197,7 +197,7 @@ static struct tcf_chain *tcf_chain_create(struct tcf_block *block,
 	list_add_tail(&chain->list, &block->chain_list);
 	chain->block = block;
 	chain->index = chain_index;
-	chain->refcnt = 1;
+	chain->refcnt = 0;
 	return chain;
 }
 
@@ -232,15 +232,15 @@ struct tcf_chain *tcf_chain_get(struct tcf_block *block, u32 chain_index,
 	struct tcf_chain *chain;
 
 	list_for_each_entry(chain, &block->chain_list, list) {
-		if (chain->index == chain_index) {
-			chain->refcnt++;
-			return chain;
-		}
+		if (chain->index == chain_index)
+			goto incref;
 	}
-	if (create)
-		return tcf_chain_create(block, chain_index);
-	else
-		return NULL;
+	chain = create ? tcf_chain_create(block, chain_index) : NULL;
+
+incref:
+	if (chain)
+		chain->refcnt++;
+	return chain;
 }
 EXPORT_SYMBOL(tcf_chain_get);
 
-- 
2.9.3