net_sched: fix a memory leak in atm_tc_init()

When tcf_block_get() fails inside atm_tc_init(),
atm_tc_put() is called to release the qdisc p->link.q.
But the flow->ref prevents it to do so, as the flow->ref
is still zero.

Fix this by moving the p->link.ref initialization before
tcf_block_get().

Fixes: 6529eaba33f0 ("net: sched: introduce tcf block infractructure")
Reported-and-tested-by: syzbot+d411cff6ab29cc2c311b@syzkaller.appspotmail.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>

diff --git a/net/sched/sch_atm.c b/net/sched/sch_atm.c
index ee12ca9f55b4fd59a6c0b826ad961ac3984c3ba2..1c281cc81f57789b787c77622cc2c026414f9c9d 100644 (file)
--- a/net/sched/sch_atm.c
+++ b/net/sched/sch_atm.c
@@ -553,16 +553,16 @@ static int atm_tc_init(struct Qdisc *sch, struct nlattr *opt,
        if (!p->link.q)
                p->link.q = &noop_qdisc;
        pr_debug("atm_tc_init: link (%p) qdisc %p\n", &p->link, p->link.q);
+       p->link.vcc = NULL;
+       p->link.sock = NULL;
+       p->link.common.classid = sch->handle;
+       p->link.ref = 1;
 
        err = tcf_block_get(&p->link.block, &p->link.filter_list, sch,
                            extack);
        if (err)
                return err;
 
-       p->link.vcc = NULL;
-       p->link.sock = NULL;
-       p->link.common.classid = sch->handle;
-       p->link.ref = 1;
        tasklet_init(&p->task, sch_atm_dequeue, (unsigned long)sch);
        return 0;
 }