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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9013DC4360C for ; Sun, 6 Oct 2019 17:33:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6904C2133F for ; Sun, 6 Oct 2019 17:33:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570383229; bh=ErQ0RgoWdfW96VS3tVihmJ/1VyvhZfVQSqm01Rnf9Tw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zIBka4D9csX2K45tDe4yA6c7DgTiVRkvi77lIXbgf69kPgliCc6c0OzYWBZvQvCKV cRsbeu5XQtMOjsiRm0WIN8g5+VvN0zPmgBh7m3KEKWwj5qezULml58JSlFG2p5gx2z tkuPcX5LVMD9rQhuyMwvFu3ujGw6ztVWv/NV29aA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729829AbfJFRdt (ORCPT ); Sun, 6 Oct 2019 13:33:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:60382 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726992AbfJFRdq (ORCPT ); Sun, 6 Oct 2019 13:33:46 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 308AF2087E; Sun, 6 Oct 2019 17:33:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570383224; bh=ErQ0RgoWdfW96VS3tVihmJ/1VyvhZfVQSqm01Rnf9Tw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b4CEYZ+n4W2xcXVvIsPyAaYtrNlluPVB1oKdP/ljA5//LgSd3P9vVE7twpJ1Tc+Ct OgNWDvM6SpkSQOnjODimD3u/h53IxPak+zhopwqTy02hAU+ygWWdHtbTW4tRaTZnhK fRjj9TSBrMW4Er37HZ3BaHvyNSbF/TuENM+7xYRE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vladimir Oltean , Vinicius Costa Gomes , "David S. Miller" Subject: [PATCH 5.2 025/137] net: sched: taprio: Avoid division by zero on invalid link speed Date: Sun, 6 Oct 2019 19:20:09 +0200 Message-Id: <20191006171211.300947133@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191006171209.403038733@linuxfoundation.org> References: <20191006171209.403038733@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vladimir Oltean [ Upstream commit 9a9251a3534745d08a92abfeca0ca467b912b5f6 ] The check in taprio_set_picos_per_byte is currently not robust enough and will trigger this division by zero, due to e.g. PHYLINK not setting kset->base.speed when there is no PHY connected: [ 27.109992] Division by zero in kernel. [ 27.113842] CPU: 1 PID: 198 Comm: tc Not tainted 5.3.0-rc5-01246-gc4006b8c2637-dirty #212 [ 27.121974] Hardware name: Freescale LS1021A [ 27.126234] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 27.133938] [] (show_stack) from [] (dump_stack+0xb0/0xc4) [ 27.141124] [] (dump_stack) from [] (Ldiv0_64+0x8/0x18) [ 27.148052] [] (Ldiv0_64) from [] (div64_u64+0xcc/0xf0) [ 27.154978] [] (div64_u64) from [] (div64_s64+0x4c/0x68) [ 27.161993] [] (div64_s64) from [] (taprio_set_picos_per_byte+0xe8/0xf4) [ 27.170388] [] (taprio_set_picos_per_byte) from [] (taprio_change+0x668/0xcec) [ 27.179302] [] (taprio_change) from [] (qdisc_create+0x1fc/0x4f4) [ 27.187091] [] (qdisc_create) from [] (tc_modify_qdisc+0x1ac/0x6f8) [ 27.195055] [] (tc_modify_qdisc) from [] (rtnetlink_rcv_msg+0x268/0x2dc) [ 27.203449] [] (rtnetlink_rcv_msg) from [] (netlink_rcv_skb+0xe0/0x114) [ 27.211756] [] (netlink_rcv_skb) from [] (netlink_unicast+0x1b4/0x22c) [ 27.219977] [] (netlink_unicast) from [] (netlink_sendmsg+0x284/0x340) [ 27.228198] [] (netlink_sendmsg) from [] (sock_sendmsg+0x14/0x24) [ 27.235988] [] (sock_sendmsg) from [] (___sys_sendmsg+0x214/0x228) [ 27.243863] [] (___sys_sendmsg) from [] (__sys_sendmsg+0x50/0x8c) [ 27.251652] [] (__sys_sendmsg) from [] (ret_fast_syscall+0x0/0x54) [ 27.259524] Exception stack(0xe8045fa8 to 0xe8045ff0) [ 27.264546] 5fa0: b6f608c8 000000f8 00000003 bed7e2f0 00000000 00000000 [ 27.272681] 5fc0: b6f608c8 000000f8 004ce54c 00000128 5d3ce8c7 00000000 00000026 00505c9c [ 27.280812] 5fe0: 00000070 bed7e298 004ddd64 b6dd1e64 Russell King points out that the ethtool API says zero is a valid return value of __ethtool_get_link_ksettings: * If it is enabled then they are read-only; if the link * is up they represent the negotiated link mode; if the link is down, * the speed is 0, %SPEED_UNKNOWN or the highest enabled speed and * @duplex is %DUPLEX_UNKNOWN or the best enabled duplex mode. So, it seems that taprio is not following the API... I'd suggest either fixing taprio, or getting agreement to change the ethtool API. The chosen path was to fix taprio. Fixes: 7b9eba7ba0c1 ("net/sched: taprio: fix picos_per_byte miscalculation") Signed-off-by: Vladimir Oltean Acked-by: Vinicius Costa Gomes Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_taprio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -668,7 +668,7 @@ static void taprio_set_picos_per_byte(st if (err < 0) goto skip; - if (ecmd.base.speed != SPEED_UNKNOWN) + if (ecmd.base.speed && ecmd.base.speed != SPEED_UNKNOWN) speed = ecmd.base.speed; skip: