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=-5.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 96E16C31E40 for ; Tue, 6 Aug 2019 19:13:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7762A208C3 for ; Tue, 6 Aug 2019 19:13:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726381AbfHFTNm (ORCPT ); Tue, 6 Aug 2019 15:13:42 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:43898 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1725948AbfHFTNm (ORCPT ); Tue, 6 Aug 2019 15:13:42 -0400 Received: (qmail 6915 invoked by uid 2102); 6 Aug 2019 15:13:41 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 6 Aug 2019 15:13:41 -0400 Date: Tue, 6 Aug 2019 15:13:41 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: syzbot cc: andreyknvl@google.com, , , , , , Subject: Re: possible deadlock in open_rio In-Reply-To: <00000000000088af91058f0fe377@google.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Thu, 1 Aug 2019, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 7f7867ff usb-fuzzer: main usb gadget fuzzer driver > git tree: https://github.com/google/kasan.git usb-fuzzer > console output: https://syzkaller.appspot.com/x/log.txt?x=136b6aec600000 > kernel config: https://syzkaller.appspot.com/x/.config?x=792eb47789f57810 > dashboard link: https://syzkaller.appspot.com/bug?extid=7bbcbe9c9ff0cd49592a > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+7bbcbe9c9ff0cd49592a@syzkaller.appspotmail.com > > ====================================================== > WARNING: possible circular locking dependency detected > 5.3.0-rc2+ #23 Not tainted > ------------------------------------------------------ Andrey: This should be completely reproducible, since it's a simple ABBA locking violation. Maybe just introducing a time delay (to avoid races and give the open() call time to run) between the gadget creation and gadget removal would be enough to do it. Is there any way you can test this? Alan Stern