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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,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 25C4BC43603 for ; Thu, 12 Dec 2019 10:57:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE4852173E for ; Thu, 12 Dec 2019 10:57:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576148226; bh=Y9duQtzzu2xe+IPa7dyGdOD1/mMKCiBYooKKncn5Z9I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=A4Jzd1V88JAi7z0yDWGJBgBkGyt+PKwhXEb3KTM8FNDEnpNen3dnSrdkXazjGbc8W 4khdOf9B6HfO8YiOohVyzFg6vcIviORTCNHDUVUqQu0nvhkOMXrb6ISwLiYbBg+rWs A7ox7gzho6u5uWTxYrt5BYB6cnE+gH2mFWL+Sm8g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728722AbfLLK5F (ORCPT ); Thu, 12 Dec 2019 05:57:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:49116 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728410AbfLLK5F (ORCPT ); Thu, 12 Dec 2019 05:57:05 -0500 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 14AEF214D8; Thu, 12 Dec 2019 10:57:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576148224; bh=Y9duQtzzu2xe+IPa7dyGdOD1/mMKCiBYooKKncn5Z9I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qUkg8WKTjygWZEUvxUim9otT0+H0k0SMsj8c9/P3OGWxhGhAI2uEOfo2iCxjQgNln g7ttTxLBNipjBZQf354ae7X6ijK5izzMGm8wvk8oTEaFLVaph54olK+ifnFvGdShnC ge437Q80lfsnRR0rh8jsyU7YnI0O1KsxWmQnQ1Lw= Date: Thu, 12 Dec 2019 11:57:01 +0100 From: Greg KH To: syzbot Cc: andriy.shevchenko@linux.intel.com, asierra@xes-inc.com, ext-kimmo.rautkoski@vaisala.com, jslaby@suse.com, kai.heng.feng@canonical.com, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, mika.westerberg@linux.intel.com, o.barta89@gmail.com, paulburton@kernel.org, sr@denx.de, syzkaller-bugs@googlegroups.com, yegorslists@googlemail.com Subject: Re: BUG: unable to handle kernel NULL pointer dereference in mem_serial_out Message-ID: <20191212105701.GB1476206@kroah.com> References: <00000000000053539a0599173973@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <00000000000053539a0599173973@google.com> Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Fri, Dec 06, 2019 at 10:25:08PM -0800, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 7ada90eb Merge tag 'drm-next-2019-12-06' of git://anongit... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=123ec282e00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=f07a23020fd7d21a > dashboard link: https://syzkaller.appspot.com/bug?extid=f4f1e871965064ae689e > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17ab090ee00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17f127f2e00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+f4f1e871965064ae689e@syzkaller.appspotmail.com > > BUG: kernel NULL pointer dereference, address: 0000000000000002 > #PF: supervisor write access in kernel mode > #PF: error_code(0x0002) - not-present page > PGD 9764a067 P4D 9764a067 PUD 9f995067 PMD 0 > Oops: 0002 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 9687 Comm: syz-executor433 Not tainted 5.4.0-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:writeb arch/x86/include/asm/io.h:65 [inline] > RIP: 0010:mem_serial_out+0x70/0x90 drivers/tty/serial/8250/8250_port.c:408 > Code: e9 00 00 00 49 8d 7c 24 40 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 > c1 ea 03 d3 e3 80 3c 02 00 75 19 48 63 db 49 03 5c 24 40 <44> 88 2b 5b 41 5c > 41 5d 5d c3 e8 81 ed cf fd eb c0 e8 da ed cf fd > RSP: 0018:ffffc90001de78e8 EFLAGS: 00010202 > RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000 > RDX: 1ffffffff181f40e RSI: ffffffff83e28776 RDI: ffffffff8c0fa070 > RBP: ffffc90001de7900 R08: ffff8880919dc340 R09: ffffed10431ee1c6 > R10: ffffed10431ee1c5 R11: ffff888218f70e2b R12: ffffffff8c0fa030 > R13: 0000000000000001 R14: ffffc90001de7a40 R15: ffffffff8c0fa188 > FS: 0000000001060880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000002 CR3: 000000009e6b8000 CR4: 00000000001406f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > serial_out drivers/tty/serial/8250/8250.h:118 [inline] > serial8250_clear_fifos.part.0+0x3a/0xb0 > drivers/tty/serial/8250/8250_port.c:557 > serial8250_clear_fifos drivers/tty/serial/8250/8250_port.c:556 [inline] > serial8250_do_startup+0x426/0x1cf0 drivers/tty/serial/8250/8250_port.c:2121 > serial8250_startup+0x62/0x80 drivers/tty/serial/8250/8250_port.c:2329 > uart_port_startup drivers/tty/serial/serial_core.c:219 [inline] > uart_startup drivers/tty/serial/serial_core.c:258 [inline] > uart_startup+0x452/0x980 drivers/tty/serial/serial_core.c:249 > uart_set_info drivers/tty/serial/serial_core.c:998 [inline] > uart_set_info_user+0x13b4/0x1cf0 drivers/tty/serial/serial_core.c:1023 > tty_tiocsserial drivers/tty/tty_io.c:2506 [inline] > tty_ioctl+0xf60/0x14f0 drivers/tty/tty_io.c:2648 > vfs_ioctl fs/ioctl.c:47 [inline] > file_ioctl fs/ioctl.c:545 [inline] > do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 > ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 > __do_sys_ioctl fs/ioctl.c:756 [inline] > __se_sys_ioctl fs/ioctl.c:754 [inline] > __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 > do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x440219 > Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff > 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007ffced648c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440219 > RDX: 0000000020000240 RSI: 000000000000541f RDI: 0000000000000003 > RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8 > R10: 0000000000401b30 R11: 0000000000000246 R12: 0000000000401aa0 > R13: 0000000000401b30 R14: 0000000000000000 R15: 0000000000000000 > Modules linked in: > CR2: 0000000000000002 > ---[ end trace eaa11ffe82f3a763 ]--- > RIP: 0010:writeb arch/x86/include/asm/io.h:65 [inline] > RIP: 0010:mem_serial_out+0x70/0x90 drivers/tty/serial/8250/8250_port.c:408 > Code: e9 00 00 00 49 8d 7c 24 40 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 > c1 ea 03 d3 e3 80 3c 02 00 75 19 48 63 db 49 03 5c 24 40 <44> 88 2b 5b 41 5c > 41 5d 5d c3 e8 81 ed cf fd eb c0 e8 da ed cf fd > RSP: 0018:ffffc90001de78e8 EFLAGS: 00010202 > RAX: dffffc0000000000 RBX: 0000000000000002 RCX: 0000000000000000 > RDX: 1ffffffff181f40e RSI: ffffffff83e28776 RDI: ffffffff8c0fa070 > RBP: ffffc90001de7900 R08: ffff8880919dc340 R09: ffffed10431ee1c6 > R10: ffffed10431ee1c5 R11: ffff888218f70e2b R12: ffffffff8c0fa030 > R13: 0000000000000001 R14: ffffc90001de7a40 R15: ffffffff8c0fa188 > FS: 0000000001060880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000002 CR3: 000000009e6b8000 CR4: 00000000001406f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > You set up a dubious memory base for your uart and then get upset when you write to that location. I don't know what to really do about this, this is a root-only operation and you are expected to know what you are doing when you attempt this. thanks, greg k-h