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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4F9DC77B7C for ; Sun, 23 Apr 2023 09:13:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229946AbjDWJN0 (ORCPT ); Sun, 23 Apr 2023 05:13:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53630 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229470AbjDWJNY (ORCPT ); Sun, 23 Apr 2023 05:13:24 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8ABB31FCC for ; Sun, 23 Apr 2023 02:13:22 -0700 (PDT) Received: from kwepemm600013.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Q42Wt2yv7zndg5; Sun, 23 Apr 2023 17:09:30 +0800 (CST) Received: from [10.174.178.46] (10.174.178.46) by kwepemm600013.china.huawei.com (7.193.23.68) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Sun, 23 Apr 2023 17:13:18 +0800 Subject: Re: BUG: divide error in ubi_attach_mtd_dev To: Richard Weinberger CC: Yu Hao , Miquel Raynal , Vignesh Raghavendra , linux-mtd , linux-kernel References: <687864524.118195.1681799447034.JavaMail.zimbra@nod.at> <977347543.226888.1682011999468.JavaMail.zimbra@nod.at> <412779912.228444.1682023015809.JavaMail.zimbra@nod.at> <1366603418.245114.1682236940160.JavaMail.zimbra@nod.at> From: Zhihao Cheng Message-ID: <951e4cf7-a0ea-b3ec-931d-e6a394ddc2ab@huawei.com> Date: Sun, 23 Apr 2023 17:13:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <1366603418.245114.1682236940160.JavaMail.zimbra@nod.at> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.46] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600013.china.huawei.com (7.193.23.68) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2023/4/23 16:02, Richard Weinberger 写道: > ----- Ursprüngliche Mail ----- >> Von: "chengzhihao1" >>>> root@syzkaller:~# cat /proc/mtd >>>> dev: size erasesize name >>>> mtd0: 00020000 00001000 “mtdram test device” >>> >>> Hmm, mtdram should be fine, erasesize is not zero. >>> >> >> I guess the zero-erasesize mtd device is dynamically generated in >> runtime, after looking through the code, I find erasesize is >> initiallized in specific flash driver and it won't be updated later(eg. >> ioctl\sysctl). And some mtd devices may have zero erasesize, eg. >> drivers/mtd/devices/mchp23k256.c[1]. Unfortunately, I don't know how to >> load/simulate this mtd, maybe it requires a real device? If we load this >> mtd device as ubi, it will trigger the problem? > > Indeed. I guess qemu can emulate such chips. > So better fix UBI to reject attaching of mtd's with erasesize being 0. > (Please note, we cannot test for MTD_NO_ERASE, this one means there is no > erase method). Phram is an exception, it has erase function but is set flag 'MTD_CAP_RAM'. May I interpret 'MTD_NO_ERASE' as erase function is not necessary?