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=-4.1 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED 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 5681AC43387 for ; Wed, 9 Jan 2019 09:28:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EBCB9206BB for ; Wed, 9 Jan 2019 09:28:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=aruba.it header.i=@aruba.it header.b="C2Tln1Qf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730405AbfAIJ2X (ORCPT ); Wed, 9 Jan 2019 04:28:23 -0500 Received: from smtpcmd02101.aruba.it ([62.149.158.101]:45857 "EHLO smtpcmd02101.aruba.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728041AbfAIJ2W (ORCPT ); Wed, 9 Jan 2019 04:28:22 -0500 X-Greylist: delayed 442 seconds by postgrey-1.27 at vger.kernel.org; Wed, 09 Jan 2019 04:28:21 EST Received: from [192.168.1.15] ([79.3.83.244]) by smtpcmd02.ad.aruba.it with bizsmtp id N9Lr1z00t5GHDdK019Ltq3; Wed, 09 Jan 2019 10:20:54 +0100 Subject: Re: UBSAN: Undefined behaviour in drivers/pps/pps.c To: Kyungtae Kim Cc: Byoungyoung Lee , DaeRyong Jeong , syzkaller@googlegroups.com, linux-kernel@vger.kernel.org References: From: Rodolfo Giometti Message-ID: <4f72df46-d2ca-e15d-4df1-fe525bbfcdd0@enneenne.com> Date: Wed, 9 Jan 2019 10:20:50 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=aruba.it; s=a1; t=1547025654; bh=RwWnrw1pSn4wXEQN2YkD0UAPqdISoKl3lyXOnEPzrfY=; h=Subject:To:From:Date:MIME-Version:Content-Type; b=C2Tln1QfQdRsl32l0dnj3kVQPSOLuMpw9XeVVDAYLFBu8e5VgzJduRseWa6mbD25B A0SlHp0i0zzxBYAwXGImaJNVEBIKy9O2OHy9tAAO48QLWr+nKAwZuZIp/jJ9T/OtOI JEAk1UK0T2WPqFvyF3AJ0R4jGOIq9VwY07GUEKvkmSfc2OMpY6vknB14LIiXqG2zc0 ZhQl4jP6l0Qjv+IJsjK/Iay49eNaiLJ5GQoztC2foEZWbeYWxQRgD+Xl2zgD4Nf5Hy EV7UWi2TmmbCq05qjYlsVTQQzgaJTeaSwsh3opFQ5qhoOP7gzNLK93wNccrWWbFKhm AKxmj5tQeuh0Q== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/01/2019 21:24, Kyungtae Kim wrote: > We report a bug in linux-4.20: "UBSAN: Undefined behaviour in drivers/pps/pps.c" > > kernel config: https://kt0755.github.io/etc/config_v4.20_stable > repro: https://kt0755.github.io/etc/repro.a6372.c > > pps_cdev_pps_fetch() lacks the bounds checking for computing > fdata->timeout.sec * HZ, that causes such integer overflow when the result > is larger than the boundary. > The patch below checks the possibility of overflow right before the > multiplication. > > ========================================= > UBSAN: Undefined behaviour in drivers/pps/pps.c:82:30 > signed integer overflow: > -7557201428062104791 * 100 cannot be represented in type 'long long int' > CPU: 0 PID: 10159 Comm: syz-executor6 Not tainted 4.20.0 #1 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0xb1/0x118 lib/dump_stack.c:113 > ubsan_epilogue+0x12/0x94 lib/ubsan.c:159 > handle_overflow+0x1cf/0x21a lib/ubsan.c:190 > __ubsan_handle_mul_overflow+0x2a/0x35 lib/ubsan.c:214 > pps_cdev_pps_fetch+0x575/0x5b0 drivers/pps/pps.c:82 > pps_cdev_ioctl+0x567/0x910 drivers/pps/pps.c:191 > vfs_ioctl fs/ioctl.c:46 [inline] > do_vfs_ioctl+0x1aa/0x1160 fs/ioctl.c:698 > ksys_ioctl+0x9e/0xb0 fs/ioctl.c:713 > __do_sys_ioctl fs/ioctl.c:720 [inline] > __se_sys_ioctl fs/ioctl.c:718 [inline] > __x64_sys_ioctl+0x7e/0xc0 fs/ioctl.c:718 > do_syscall_64+0xbe/0x4f0 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x4497b9 > Code: e8 8c 9f 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 9b 6b fc ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f8cf875bc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00007f8cf875c6cc RCX: 00000000004497b9 > RDX: 0000000020000240 RSI: 00000000c00870a4 RDI: 0000000000000014 > RBP: 000000000071bea0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff > R13: 0000000000005c10 R14: 00000000006eecb0 R15: 00007f8cf875c700 > ========================================= > > --- > drivers/pps/pps.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c > index 8febacb..66002e1 100644 > --- a/drivers/pps/pps.c > +++ b/drivers/pps/pps.c > @@ -79,6 +79,8 @@ static int pps_cdev_pps_fetch(struct pps_device > *pps, struct pps_fdata *fdata) > dev_dbg(pps->dev, "timeout %lld.%09d\n", > (long long) fdata->timeout.sec, > fdata->timeout.nsec); > + if (fdata->timeout.sec > S64_MAX / HZ) > + return -EINVAL; > ticks = fdata->timeout.sec * HZ; > ticks += fdata->timeout.nsec / (NSEC_PER_SEC / HZ); It looks good to me. Do you think is better adding a check for timeout.nsec also? Now you have to produce a patch according to linux/Documentation/process/submitting-patches.rst and then submitting it! :-) Ciao, Rodolfo -- GNU/Linux Solutions e-mail: giometti@enneenne.com Linux Device Driver giometti@linux.it Embedded Systems phone: +39 349 2432127 UNIX programming skype: rodolfo.giometti