Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+8325e509a1bf83ec741d@syzkaller.appspotmail.com,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        Jiri Pirko <jiri@resnulli.us>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.6 08/38] net_sched: fix a missing refcnt in tcindex_init()
Date:   Sat, 11 Apr 2020 14:09:45 +0200
Message-Id: <20200411115500.208523742@linuxfoundation.org>
In-Reply-To: <20200411115459.324496182@linuxfoundation.org>
References: <20200411115459.324496182@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Cong Wang <xiyou.wangcong@gmail.com>

[ Upstream commit a8eab6d35e22f4f21471f16147be79529cd6aaf7 ]

The initial refcnt of struct tcindex_data should be 1,
it is clear that I forgot to set it to 1 in tcindex_init().
This leads to a dec-after-zero warning.

Reported-by: syzbot+8325e509a1bf83ec741d@syzkaller.appspotmail.com
Fixes: 304e024216a8 ("net_sched: add a temporary refcnt for struct tcindex_data")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sched/cls_tcindex.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/sched/cls_tcindex.c
+++ b/net/sched/cls_tcindex.c
@@ -151,6 +151,7 @@ static int tcindex_init(struct tcf_proto
 	p->mask = 0xffff;
 	p->hash = DEFAULT_HASH_SIZE;
 	p->fall_through = 1;
+	refcount_set(&p->refcnt, 1); /* Paired with tcindex_destroy_work() */
 
 	rcu_assign_pointer(tp->root, p);
 	return 0;