From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933842AbcHNMGI (ORCPT ); Sun, 14 Aug 2016 08:06:08 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52269 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933173AbcHNL1l (ORCPT ); Sun, 14 Aug 2016 07:27:41 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Eric Dumazet" , "Stephen Hemminger" , "Jamal Hadi Salim" , "David S. Miller" , "WANG Cong" Date: Sat, 13 Aug 2016 18:42:51 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 192/305] netem: fix a use after free In-Reply-To: X-SA-Exim-Connect-IP: 92.40.249.202 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.37-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 21de12ee5568fd1aec47890c72967abf791ac80a upstream. If the packet was dropped by lower qdisc, then we must not access it later. Save qdisc_pkt_len(skb) in a temp variable. Fixes: 2ccccf5fb43f ("net_sched: update hierarchical backlog too") Signed-off-by: Eric Dumazet Cc: WANG Cong Cc: Jamal Hadi Salim Cc: Stephen Hemminger Signed-off-by: David S. Miller [bwh: Backported to 3.16: not using qdisc_qstats_drop()] Signed-off-by: Ben Hutchings --- net/sched/sch_netem.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -606,14 +606,14 @@ deliver: #endif if (q->qdisc) { + unsigned int pkt_len = qdisc_pkt_len(skb); int err = qdisc_enqueue(skb, q->qdisc); - if (unlikely(err != NET_XMIT_SUCCESS)) { - if (net_xmit_drop_count(err)) { - sch->qstats.drops++; - qdisc_tree_reduce_backlog(sch, 1, - qdisc_pkt_len(skb)); - } + if (err != NET_XMIT_SUCCESS && + net_xmit_drop_count(err)) { + sch->qstats.drops++; + qdisc_tree_reduce_backlog(sch, 1, + pkt_len); } goto tfifo_dequeue; }