[PATCH 5.6 08/38] net_sched: fix a missing refcnt in tcindex_init()

Greg Kroah-Hartman
2020-04-11T12:22:20Z

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;