net_sched: fix error path in red_init()

When ->init() fails, ->destroy() is called to clean up.
So it is unnecessary to clean up in red_init(), and it
would cause some refcount underflow.

Fixes: aee9caa03fc3 ("net: sched: sch_red: Add qevents "early_drop" and "mark"")
Reported-and-tested-by: syzbot+b33c1cb0a30ebdc8a5f9@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+e5ea5f8a3ecfd4427a1c@syzkaller.appspotmail.com
Cc: Petr Machata <petrm@mellanox.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
index deac82f..e89fab6 100644 (file)
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -353,23 +353,11 @@ static int red_init(struct Qdisc *sch, struct nlattr *opt,
                              FLOW_BLOCK_BINDER_TYPE_RED_EARLY_DROP,
                              tb[TCA_RED_EARLY_DROP_BLOCK], extack);
        if (err)
-               goto err_early_drop_init;
-
-       err = tcf_qevent_init(&q->qe_mark, sch,
-                             FLOW_BLOCK_BINDER_TYPE_RED_MARK,
-                             tb[TCA_RED_MARK_BLOCK], extack);
-       if (err)
-               goto err_mark_init;
-
-       return 0;
+               return err;
 
-err_mark_init:
-       tcf_qevent_destroy(&q->qe_early_drop, sch);
-err_early_drop_init:
-       del_timer_sync(&q->adapt_timer);
-       red_offload(sch, false);
-       qdisc_put(q->qdisc);
-       return err;
+       return tcf_qevent_init(&q->qe_mark, sch,
+                              FLOW_BLOCK_BINDER_TYPE_RED_MARK,
+                              tb[TCA_RED_MARK_BLOCK], extack);
 }
 
 static int red_change(struct Qdisc *sch, struct nlattr *opt,