From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966306AbdKPR43 (ORCPT ); Thu, 16 Nov 2017 12:56:29 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:38236 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966129AbdKPRvz (ORCPT ); Thu, 16 Nov 2017 12:51:55 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Davide Caratti , Jiri Kosina , Eric Dumazet , Jamal Hadi Salim , Cong Wang , "David S. Miller" Subject: [PATCH 4.13 33/44] net_sched: avoid matching qdisc with zero handle Date: Thu, 16 Nov 2017 18:42:57 +0100 Message-Id: <20171116172825.090694932@linuxfoundation.org> X-Mailer: git-send-email 2.15.0 In-Reply-To: <20171116172823.336649076@linuxfoundation.org> References: <20171116172823.336649076@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cong Wang [ Upstream commit 50317fce2cc70a2bbbc4b42c31bbad510382a53c ] Davide found the following script triggers a NULL pointer dereference: ip l a name eth0 type dummy tc q a dev eth0 parent :1 handle 1: htb This is because for a freshly created netdevice noop_qdisc is attached and when passing 'parent :1', kernel actually tries to match the major handle which is 0 and noop_qdisc has handle 0 so is matched by mistake. Commit 69012ae425d7 tries to fix a similar bug but still misses this case. Handle 0 is not a valid one, should be just skipped. In fact, kernel uses it as TC_H_UNSPEC. Fixes: 69012ae425d7 ("net: sched: fix handling of singleton qdiscs with qdisc_hash") Fixes: 59cc1f61f09c ("net: sched:convert qdisc linked list to hashtable") Reported-by: Davide Caratti Cc: Jiri Kosina Cc: Eric Dumazet Cc: Jamal Hadi Salim Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_api.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -307,6 +307,8 @@ struct Qdisc *qdisc_lookup(struct net_de { struct Qdisc *q; + if (!handle) + return NULL; q = qdisc_match_from_root(dev->qdisc, handle); if (q) goto out;