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=-7.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_PASS,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 57900C10F12 for ; Mon, 15 Apr 2019 19:09:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25C7320880 for ; Mon, 15 Apr 2019 19:09:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555355373; bh=A7Ui/SD/tqefETsYaRJrobK3ObaTe4rAJ6g3oyvZqXE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=VgbQlBLqqQZ1JKyPikaRU9Mq5N3HoYfn8hAuB4uTi3OKpimgWMRIuVHIGGU1e5zGC uEkYZIZ0g8OHgZeHGtSijaR2iB58BdGInv9TgT0LGgR/yHNqNvsqXlqMYXFsSBapWL d1WFEC+Hpy229pOBiMKUQDrbo7aep2PSh+NGDv4g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730754AbfDOTJc (ORCPT ); Mon, 15 Apr 2019 15:09:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:45206 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730729AbfDOTJ1 (ORCPT ); Mon, 15 Apr 2019 15:09:27 -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 E530D20651; Mon, 15 Apr 2019 19:09:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555355366; bh=A7Ui/SD/tqefETsYaRJrobK3ObaTe4rAJ6g3oyvZqXE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DTCr/Ml7g0KoEp39f+ctkw1lvhI24TEp0zVUGUY3TaO6U4VgELUToLvjdme6OlmY2 BcLK6veJrICOeuyY1mJ9IS1bLRfBOgHINcD5bzuqsmkhjZClihE3bdUvoLSPt4i4rJ sYP8HOm6K6RfXKH1KFj5wN/2kJ4yUhm2wNsWEP/8= Date: Mon, 15 Apr 2019 21:00:54 +0200 From: Greg Kroah-Hartman To: Andrey Konovalov Cc: "Gustavo A. R. Silva" , Alan Stern , Kernel development list , USB list , syzkaller-bugs Subject: Re: INFO: task hung in usb_kill_urb Message-ID: <20190415190054.GA10359@kroah.com> References: <0000000000006f1596058653d991@google.com> <52ac871b-ac61-432e-3a85-47b8e97233d2@embeddedor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52ac871b-ac61-432e-3a85-47b8e97233d2@embeddedor.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 15, 2019 at 01:39:57PM -0500, Gustavo A. R. Silva wrote: > > > On 4/15/19 12:48 PM, Andrey Konovalov wrote: > > On Fri, Apr 12, 2019 at 9:46 PM Alan Stern wrote: > >> > >> Andrey: > >> > >> It's really hard to tell just what's going on here. > >> > >> On Fri, 12 Apr 2019, syzbot wrote: > >> > >>> Hello, > >>> > >>> syzbot found the following crash on: > >>> > >>> HEAD commit: 9a33b369 usb-fuzzer: main usb gadget fuzzer driver > >>> git tree: https://github.com/google/kasan/tree/usb-fuzzer > >>> console output: https://syzkaller.appspot.com/x/log.txt?x=14c4c1af200000 > >>> kernel config: https://syzkaller.appspot.com/x/.config?x=23e37f59d94ddd15 > >>> dashboard link: https://syzkaller.appspot.com/bug?extid=d919b0f29d7b5a4994b9 > >>> compiler: gcc (GCC) 9.0.0 20181231 (experimental) > >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14410dbb200000 > >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12f0acd3200000 > >>> > >>> IMPORTANT: if you fix the bug, please add the following tag to the commit: > >>> Reported-by: syzbot+d919b0f29d7b5a4994b9@syzkaller.appspotmail.com > >>> > >>> usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > >>> usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > >>> usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > >>> usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > >>> usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > >>> INFO: task kworker/0:2:532 blocked for more than 143 seconds. > >>> Not tainted 5.1.0-rc4-319354-g9a33b36 #3 > >>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > >>> kworker/0:2 D26656 532 2 0x80000000 > >>> Workqueue: usb_hub_wq hub_event > >>> Call Trace: > >>> schedule+0x8f/0x180 kernel/sched/core.c:3562 > >>> usb_kill_urb drivers/usb/core/urb.c:695 [inline] > >>> usb_kill_urb+0x22a/0x2c0 drivers/usb/core/urb.c:687 > >>> usb_start_wait_urb+0x257/0x4d0 drivers/usb/core/message.c:63 > >>> usb_internal_control_msg drivers/usb/core/message.c:101 [inline] > >>> usb_control_msg+0x321/0x4a0 drivers/usb/core/message.c:152 > >> > >> It looks like something is stuck waiting for usb_kill_urb() to finish. > >> But what happened before that? > > > > This crash is somewhat special. It happens quite often during USB > > fuzzing, but at the same time it's a hang, which makes it a bit harder > > debug. I initially thought that is somehow related to my custom USB > > fuzzing kernel patches, but then I saw that someone else hit this > > issue while doing USB fuzzing in a completely different way that > > doesn't require kernel modifications. So it might be an actual issue > > in the kernel. > > > > The full console output is provided by the syzbot, but I guess it's > > not very useful in this case. I've just made sure that this issue is > > manually reproducible, so we can easily retest it with debug patches > > (syzbot should be also able to do that via the syz test command). Or > > is there a way to turn on some verbose mode to see some USB debug > > messages? > > > >> > >> I can't tell from the reproducer source, because it uses a bunch of > >> special stuff you added in your usb-fuzzer tree. > >> > >> Alan Stern > >> > > > > I understand, for now I guess the simpler way to debug this is to run > > the reproducer. I'll write you and Greg a separate email regarding all > > that special stuff that I added. > > > > Hi Andrey, > > Please, CC me on that email too. Please cc: all of linux-usb@vger.kernel.org, no need to keep anything private. thanks, greg k-h