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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_MUTT 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 1EFA4C32789 for ; Sat, 3 Nov 2018 02:03:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D64942082D for ; Sat, 3 Nov 2018 02:03:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="H6x9dKCD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D64942082D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728542AbeKCLM4 (ORCPT ); Sat, 3 Nov 2018 07:12:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:39066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725865AbeKCLM4 (ORCPT ); Sat, 3 Nov 2018 07:12:56 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 CB43B2082D; Sat, 3 Nov 2018 02:03:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541210600; bh=DVyfJiNMPFmLT8oHmrKpLDvgCalTYuZbY1PdPOU5ZLQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H6x9dKCDo91eUFBHHgZ7V49dpy3SDySQQnMZ0kzIOM2yQQTVkFU502Z3k28Y08H5j qMkiiIICk4obeEcmP2e6VQctQoNg0AZVnvH7Ak7NBMZiiJGMLnc8f1HFuyJ4SSYWv8 Jjyk6fj2o/hw0NQI6Npp96c6P/IRRIQ3X/e67xBE= Date: Fri, 2 Nov 2018 22:03:18 -0400 From: Sasha Levin To: Josh Hunt Cc: Greg Kroah-Hartman , LKML , stable , stephen@networkplumber.org, Eric Dumazet , soheil@google.com, weiwan@google.com, willemb@google.com, cpaasch@apple.com Subject: Re: [PATCH 4.14 106/143] sch_netem: restore skb->dev after dequeuing from the rbtree Message-ID: <20181103020318.GL194472@sasha-vm> References: <20181102182857.064326086@linuxfoundation.org> <20181102182906.323035183@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 02, 2018 at 04:28:04PM -0700, Josh Hunt wrote: >On Fri, Nov 2, 2018 at 12:00 PM Greg Kroah-Hartman > wrote: >> >> 4.14-stable review patch. If anyone has any objections, please let me know. >> >> ------------------ >> >> Upstream commit bffa72cf7f9d ("net: sk_buff rbnode reorg") got >> backported as commit 6b921536f170 ("net: sk_buff rbnode reorg") into the >> v4.14.x-tree. >> >> However, the backport does not include the changes in sch_netem.c >> >> We need these, as otherwise the skb->dev pointer is not set when >> dequeueing from the netem rbtree, resulting in a panic: >> >> [ 15.427748] BUG: unable to handle kernel NULL pointer dereference at 00000000000000d0 >> [ 15.428863] IP: netif_skb_features+0x24/0x230 >> [ 15.429402] PGD 0 P4D 0 >> [ 15.429733] Oops: 0000 [#1] SMP PTI >> [ 15.430169] Modules linked in: >> [ 15.430614] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.14.77.mptcp #77 >> [ 15.431497] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.5.1 01/01/2011 >> [ 15.432568] task: ffff88042db19680 task.stack: ffffc90000070000 >> [ 15.433356] RIP: 0010:netif_skb_features+0x24/0x230 >> [ 15.433977] RSP: 0018:ffff88043fd83e70 EFLAGS: 00010286 >> [ 15.434665] RAX: ffff880429ad80c0 RBX: ffff88042bd0e400 RCX: ffff880429ad8000 >> [ 15.435585] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88042bd0e400 >> [ 15.436551] RBP: ffff88042bd0e400 R08: ffff88042a4b6c9c R09: 0000000000000001 >> [ 15.437485] R10: 0000000000000004 R11: 0000000000000000 R12: ffff88042c700000 >> [ 15.438393] R13: ffff88042c700000 R14: ffff88042a4b6c00 R15: ffff88042c6bb000 >> [ 15.439315] FS: 0000000000000000(0000) GS:ffff88043fd80000(0000) knlGS:0000000000000000 >> [ 15.440314] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [ 15.441084] CR2: 00000000000000d0 CR3: 000000042c374000 CR4: 00000000000006e0 >> [ 15.442016] Call Trace: >> [ 15.442333] >> [ 15.442596] validate_xmit_skb+0x17/0x270 >> [ 15.443134] validate_xmit_skb_list+0x38/0x60 >> [ 15.443698] sch_direct_xmit+0x102/0x190 >> [ 15.444198] __qdisc_run+0xe3/0x240 >> [ 15.444671] net_tx_action+0x121/0x140 >> [ 15.445177] __do_softirq+0xe2/0x224 >> [ 15.445654] irq_exit+0xbf/0xd0 >> [ 15.446072] smp_apic_timer_interrupt+0x5d/0x90 >> [ 15.446654] apic_timer_interrupt+0x7d/0x90 >> [ 15.447185] >> [ 15.447460] RIP: 0010:native_safe_halt+0x2/0x10 >> [ 15.447992] RSP: 0018:ffffc90000073f10 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10 >> [ 15.449008] RAX: ffffffff816667d0 RBX: ffffffff820946b0 RCX: 0000000000000000 >> [ 15.449895] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 >> [ 15.450768] RBP: ffffffff82026940 R08: 00000004e858e5e1 R09: ffff88042a4b6d58 >> [ 15.451643] R10: 0000000000000000 R11: 000000d0d56879bb R12: 0000000000000000 >> [ 15.452478] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 >> [ 15.453340] ? __sched_text_end+0x2/0x2 >> [ 15.453835] default_idle+0xf/0x20 >> [ 15.454259] do_idle+0x170/0x200 >> [ 15.454653] cpu_startup_entry+0x14/0x20 >> [ 15.455142] secondary_startup_64+0xa5/0xb0 >> [ 15.455715] Code: 1f 84 00 00 00 00 00 55 53 48 89 fd 48 83 ec 08 8b 87 bc 00 00 00 48 8b 8f c0 00 00 00 0f b6 97 81 00 00 00 48 8b 77 10 48 01 c8 <48> 8b 9 >> [ 15.458138] RIP: netif_skb_features+0x24/0x230 RSP: ffff88043fd83e70 >> [ 15.458933] CR2: 00000000000000d0 >> [ 15.459352] ---[ end trace 083925903ae60570 ]--- >> >> Fixes: 6b921536f170 ("net: sk_buff rbnode reorg") >> Cc: Stephen Hemminger >> Cc: Eric Dumazet >> Cc: Soheil Hassas Yeganeh >> Cc: Wei Wang >> Cc: Willem de Bruijn >> Signed-off-by: Christoph Paasch >> Signed-off-by: Sasha Levin >> --- >> net/sched/sch_netem.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c >> index 2a2ab6bfe5d8..3d325b840802 100644 >> --- a/net/sched/sch_netem.c >> +++ b/net/sched/sch_netem.c >> @@ -624,6 +624,10 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch) >> skb->next = NULL; >> skb->prev = NULL; >> skb->tstamp = netem_skb_cb(skb)->tstamp_save; >> + /* skb->dev shares skb->rbnode area, >> + * we need to restore its value. >> + */ >> + skb->dev = qdisc_dev(sch); >> >> #ifdef CONFIG_NET_CLS_ACT >> /* >> -- >> 2.17.1 > >I was seeing this crash on 4.14.78 and this patch fixes it. > >Thanks! Thanks for confirming Josh! -- Thanks, Sasha