From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D7E7C43334 for ; Thu, 30 Jun 2022 14:03:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235868AbiF3ODb (ORCPT ); Thu, 30 Jun 2022 10:03:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45050 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236477AbiF3OC3 (ORCPT ); Thu, 30 Jun 2022 10:02:29 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B6F25073A; Thu, 30 Jun 2022 06:52:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 0CD9BB82AF3; Thu, 30 Jun 2022 13:52:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C545C34115; Thu, 30 Jun 2022 13:52:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656597171; bh=3KY1oaQSn0G41Rhl1/3pb9fLEjbbzfQpc6xmm+S8BKY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2VT6hAUd3ZSJeg92CuESZuSpmHvhhYlKPbAUzuB929eXzqf32EWG1vxCV6YSVYl31 PMmMrfuerv+4BaVL9wIHbpz8X7Bz+Uf2F7PrG3UF50F4VeYak1aMuqhzoWTIIhLgsx fB11664Ii8rkt1u7IO5QV9nZJcd6BWQ8iu7IAneU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yuming Chen , Cong Wang , Peilin Ye , Stephen Hemminger , Jakub Kicinski , Sasha Levin Subject: [PATCH 4.19 13/49] net/sched: sch_netem: Fix arithmetic in netem_dump() for 32-bit platforms Date: Thu, 30 Jun 2022 15:46:26 +0200 Message-Id: <20220630133234.292428034@linuxfoundation.org> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220630133233.910803744@linuxfoundation.org> References: <20220630133233.910803744@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peilin Ye [ Upstream commit a2b1a5d40bd12b44322c2ccd40bb0ec1699708b6 ] As reported by Yuming, currently tc always show a latency of UINT_MAX for netem Qdisc's on 32-bit platforms: $ tc qdisc add dev dummy0 root netem latency 100ms $ tc qdisc show dev dummy0 qdisc netem 8001: root refcnt 2 limit 1000 delay 275s 275s ^^^^^^^^^^^^^^^^ Let us take a closer look at netem_dump(): qopt.latency = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->latency, UINT_MAX); qopt.latency is __u32, psched_tdiff_t is signed long, (psched_tdiff_t)(UINT_MAX) is negative for 32-bit platforms, so qopt.latency is always UINT_MAX. Fix it by using psched_time_t (u64) instead. Note: confusingly, users have two ways to specify 'latency': 1. normally, via '__u32 latency' in struct tc_netem_qopt; 2. via the TCA_NETEM_LATENCY64 attribute, which is s64. For the second case, theoretically 'latency' could be negative. This patch ignores that corner case, since it is broken (i.e. assigning a negative s64 to __u32) anyways, and should be handled separately. Thanks Ted Lin for the analysis [1] . [1] https://github.com/raspberrypi/linux/issues/3512 Reported-by: Yuming Chen Fixes: 112f9cb65643 ("netem: convert to qdisc_watchdog_schedule_ns") Reviewed-by: Cong Wang Signed-off-by: Peilin Ye Acked-by: Stephen Hemminger Link: https://lore.kernel.org/r/20220616234336.2443-1-yepeilin.cs@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/sch_netem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index ad400f4f9a2d..31793af1a77b 100644 --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -1120,9 +1120,9 @@ static int netem_dump(struct Qdisc *sch, struct sk_buff *skb) struct tc_netem_rate rate; struct tc_netem_slot slot; - qopt.latency = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->latency), + qopt.latency = min_t(psched_time_t, PSCHED_NS2TICKS(q->latency), UINT_MAX); - qopt.jitter = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->jitter), + qopt.jitter = min_t(psched_time_t, PSCHED_NS2TICKS(q->jitter), UINT_MAX); qopt.limit = q->limit; qopt.loss = q->loss; -- 2.35.1