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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 0A55EC433B4 for ; Wed, 14 Apr 2021 16:16:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D555661168 for ; Wed, 14 Apr 2021 16:16:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352648AbhDNQQu (ORCPT ); Wed, 14 Apr 2021 12:16:50 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:50939 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352561AbhDNQQt (ORCPT ); Wed, 14 Apr 2021 12:16:49 -0400 Received: from fsav405.sakura.ne.jp (fsav405.sakura.ne.jp [133.242.250.104]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 13EGGGMe078064; Thu, 15 Apr 2021 01:16:16 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav405.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav405.sakura.ne.jp); Thu, 15 Apr 2021 01:16:16 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav405.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 13EGGG3q078059 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Thu, 15 Apr 2021 01:16:16 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [syzbot] unexpected kernel reboot (4) To: Andrey Konovalov , Dmitry Vyukov Cc: syzbot , LKML , syzkaller-bugs , "open list:HID CORE LAYER" References: <000000000000301a4d05bfe14b8f@google.com> From: Tetsuo Handa Message-ID: Date: Thu, 15 Apr 2021 01:16:13 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/04/15 0:39, Andrey Konovalov wrote: > On Wed, Apr 14, 2021 at 7:45 AM Dmitry Vyukov wrote: >> >> On Tue, Apr 13, 2021 at 11:27 PM syzbot >> wrote: >>> >>> Hello, >>> >>> syzbot found the following issue on: >>> >>> HEAD commit: 89698bec Merge tag 'm68knommu-for-v5.12-rc7' of git://git... >>> git tree: upstream >>> console output: https://syzkaller.appspot.com/x/log.txt?x=1243fcfed00000 >>> kernel config: https://syzkaller.appspot.com/x/.config?x=b234ddbbe2953747 >>> dashboard link: https://syzkaller.appspot.com/bug?extid=9ce030d4c89856b27619 >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=173e92fed00000 >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1735da2ed00000 >>> >>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>> Reported-by: syzbot+9ce030d4c89856b27619@syzkaller.appspotmail.com >>> >>> output_len: 0x000000000e74eb68 >>> kernel_total_size: 0x000000000f226000 >>> needed_size: 0x000000000f400000 >>> trampoline_32bit: 0x000000000009d000 >>> Decompressing Linux... Parsing ELF... done. >>> Booting the kernel. >> >> +linux-input >> >> The reproducer connects some USB HID device and communicates with the driver. >> Previously we observed reboots because HID devices can trigger reboot >> SYSRQ, but we disable it with "CONFIG_MAGIC_SYSRQ is not set". >> How else can a USB device reboot the machine? Is it possible to disable it? >> I don't see any direct includes of in drivers/usb/* > > This happens when a keyboard sends the Ctrl+Alt+Del sequence, see > fn_boot_it()->ctrl_alt_del() in drivers/tty/vt/keyboard.c. > > There was a patchset by Tetsuo [1] to suppress this, but I think it > was abandoned. Not abandoned; I'm waiting for you to join the discussion. But for right now I'm trying to merge LOCKDEP's capacity tuning patch for https://github.com/google/syzkaller/pull/2535 in the next merge window. I still believe that ctrl_alt_del() etc. should be initially controlled via kernel config options (despite Linus's objection at https://lore.kernel.org/lkml/CAHk-=wgz=7MGxxX-tmMmdCsKyYJkuyxNc-4uLP=e_eEV=OzUaw@mail.gmail.com/ ), for we will need several trials and errors (and an effort to avoid kernel size bloating like https://lkml.kernel.org/r/YD57hjaSmsYapHnQ@alley still remains) before we can determine usable units for allow toggling via kernel command line options. > > (This reminds of a somewhat related syzkaller issue: > https://github.com/google/syzkaller/issues/1824; it relies on a > similar reproducer.) > > [1] https://groups.google.com/g/syzkaller/c/7wCmrGlLgm0/m/5yG6HVtbBQAJ >