From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net] net: sched: red: avoid hashing NULL child
Date: Fri, 18 May 2018 13:53:12 -0400 (EDT)
Message-ID: <20180518.135312.896740897180570132.davem@davemloft.net>
References: <286744ab66eaa07d61d5d8ce8a07cb0b1615d35c.1526647813.git.pabeni@redhat.com>
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Cc: netdev@vger.kernel.org, jhs@mojatatu.com, xiyou.wangcong@gmail.com,
        jiri@resnulli.us, liuhangbin@gmail.com, jkosina@suse.cz
To: pabeni@redhat.com
Return-path: <netdev-owner@vger.kernel.org>
Received: from shards.monkeyblade.net ([184.105.139.130]:48198 "EHLO
        shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1752428AbeERRxO (ORCPT
        <rfc822;netdev@vger.kernel.org>); Fri, 18 May 2018 13:53:14 -0400
In-Reply-To: <286744ab66eaa07d61d5d8ce8a07cb0b1615d35c.1526647813.git.pabeni@redhat.com>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

From: Paolo Abeni <pabeni@redhat.com>
Date: Fri, 18 May 2018 14:51:44 +0200

> Hangbin reported an Oops triggered by the syzkaller qdisc rules:
 ...
> When a red qdisc is updated with a 0 limit, the child qdisc is left
> unmodified, no additional scheduler is created in red_change(),
> the 'child' local variable is rightfully NULL and must not add it
> to the hash table.
> 
> This change addresses the above issue moving qdisc_hash_add() right
> after the child qdisc creation. It additionally removes unneeded checks
> for noop_qdisc.
> 
> Reported-by: Hangbin Liu <liuhangbin@gmail.com>
> Fixes: 49b499718fa1 ("net: sched: make default fifo qdiscs appear in the dump")
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Applied and queued up for -stable, thanks Paolo.