From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: [Patch net] net_sched: check noop_qdisc before qdisc_hash_add() Date: Tue, 4 Apr 2017 18:51:30 -0700 Message-ID: <1491357091-27064-1-git-send-email-xiyou.wangcong@gmail.com> Cc: dvyukov@google.com, edumazet@google.com, Cong Wang , Jiri Kosina To: netdev@vger.kernel.org Return-path: Received: from mail-pf0-f194.google.com ([209.85.192.194]:36199 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753178AbdDEBvr (ORCPT ); Tue, 4 Apr 2017 21:51:47 -0400 Received: by mail-pf0-f194.google.com with SMTP id r137so7051069pfr.3 for ; Tue, 04 Apr 2017 18:51:47 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: Dmitry reported a crash when injecting faults in attach_one_default_qdisc() and dev->qdisc is still a noop_disc, the check before qdisc_hash_add() fails to catch it because it tests NULL. We should test against noop_qdisc since it is the default qdisc at this point. Fixes: 59cc1f61f09c ("net: sched: convert qdisc linked list to hashtable") Reported-by: Dmitry Vyukov Cc: Jiri Kosina Signed-off-by: Cong Wang --- net/sched/sch_generic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index b052b27..1a2f9e9 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -794,7 +794,7 @@ static void attach_default_qdiscs(struct net_device *dev) } } #ifdef CONFIG_NET_SCHED - if (dev->qdisc) + if (dev->qdisc != &noop_qdisc) qdisc_hash_add(dev->qdisc); #endif } -- 2.5.5