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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS 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 9CD17C10F11 for ; Mon, 22 Apr 2019 17:53:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 703CE20B1F for ; Mon, 22 Apr 2019 17:53:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728313AbfDVRxT (ORCPT ); Mon, 22 Apr 2019 13:53:19 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:38298 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1727480AbfDVRxS (ORCPT ); Mon, 22 Apr 2019 13:53:18 -0400 Received: (qmail 6556 invoked by uid 2102); 22 Apr 2019 13:53:17 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 22 Apr 2019 13:53:17 -0400 Date: Mon, 22 Apr 2019 13:53:17 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: syzbot cc: andreyknvl@google.com, , Kernel development list , USB list , , Subject: Re: general protection fault in __dev_printk In-Reply-To: <00000000000029431d0586d10813@google.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 18 Apr 2019, syzbot wrote: > syzbot has found a reproducer for the following crash on: > > HEAD commit: d34f9519 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=10adfe6b200000 > kernel config: https://syzkaller.appspot.com/x/.config?x=c73d1bb5aeaeae20 > dashboard link: https://syzkaller.appspot.com/bug?extid=2eb9121678bdb36e6d57 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=145cb7e3200000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17f8bd2d200000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+2eb9121678bdb36e6d57@syzkaller.appspotmail.com > > yurex 1-1:0.150: yurex_interrupt - unknown status received: -71 > usb 1-1: USB disconnect, device number 112 > yurex 1-1:0.150: yurex_interrupt - unknown status received: -71 > kasan: CONFIG_KASAN_INLINE enabled > kasan: GPF could be caused by NULL-ptr deref or user memory access > general protection fault: 0000 [#1] SMP KASAN PTI Andrey: This original bug report included a "USB disconnect" line, as shown above. The newer results, for runs with my patches added, do not. At least, if such a line was present, it didn't show up in the console output files -- the most recent one contains nothing but repeats of that "yurex_interrupt - unknown status received: -71" line, although for devices on multiple buses. Is there any way to get more information about what's happening, such as a complete kernel log? And perhaps to run the test with just a single dummy-hcd bus instead of 6? At this point, I suspect the original general protection fault in the yurex driver has been fixed, but something else in dummy-hcd may be causing the rcu-detected stalls. Alan Stern