From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932657Ab2JJXVx (ORCPT ); Wed, 10 Oct 2012 19:21:53 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:40947 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757751Ab2JJWyj (ORCPT ); Wed, 10 Oct 2012 18:54:39 -0400 X-Sasl-enc: KS9rjAsZrCPJhIzaWlvMBShprl5XyfgKhkTvKaYPsv5G 1349909678 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Paolo Valente , "David S. Miller" Subject: [ 040/133] pkt_sched: fix virtual-start-time update in QFQ Date: Thu, 11 Oct 2012 07:51:06 +0900 Message-Id: <20121010224901.709840828@linuxfoundation.org> X-Mailer: git-send-email 1.8.0.rc0.18.gf84667d In-Reply-To: <20121010224854.313159132@linuxfoundation.org> References: <20121010224854.313159132@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paolo Valente [ Upstream commit 71261956973ba9e0637848a5adb4a5819b4bae83 ] If the old timestamps of a class, say cl, are stale when the class becomes active, then QFQ may assign to cl a much higher start time than the maximum value allowed. This may happen when QFQ assigns to the start time of cl the finish time of a group whose classes are characterized by a higher value of the ratio max_class_pkt/weight_of_the_class with respect to that of cl. Inserting a class with a too high start time into the bucket list corrupts the data structure and may eventually lead to crashes. This patch limits the maximum start time assigned to a class. Signed-off-by: Paolo Valente Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_qfq.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -831,7 +831,10 @@ static void qfq_update_start(struct qfq_ if (mask) { struct qfq_group *next = qfq_ffs(q, mask); if (qfq_gt(roundedF, next->F)) { - cl->S = next->F; + if (qfq_gt(limit, next->F)) + cl->S = next->F; + else /* preserve timestamp correctness */ + cl->S = limit; return; } }