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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0428C433EF for ; Fri, 15 Oct 2021 07:37:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9812160FE3 for ; Fri, 15 Oct 2021 07:37:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236394AbhJOHjN (ORCPT ); Fri, 15 Oct 2021 03:39:13 -0400 Received: from smtp181.sjtu.edu.cn ([202.120.2.181]:42162 "EHLO smtp181.sjtu.edu.cn" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236258AbhJOHio (ORCPT ); Fri, 15 Oct 2021 03:38:44 -0400 Received: from proxy02.sjtu.edu.cn (smtp188.sjtu.edu.cn [202.120.2.188]) by smtp181.sjtu.edu.cn (Postfix) with ESMTPS id D20AF1006D5BA; Fri, 15 Oct 2021 15:36:33 +0800 (CST) Received: from localhost (localhost.localdomain [127.0.0.1]) by proxy02.sjtu.edu.cn (Postfix) with ESMTP id ED7E6200B8924; Fri, 15 Oct 2021 15:36:30 +0800 (CST) X-Virus-Scanned: amavisd-new at Received: from proxy02.sjtu.edu.cn ([127.0.0.1]) by localhost (proxy02.sjtu.edu.cn [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id D8EEzls3b3t7; Fri, 15 Oct 2021 15:36:30 +0800 (CST) Received: from [192.168.10.98] (unknown [202.120.40.82]) (Authenticated sender: qtxuning1999@sjtu.edu.cn) by proxy02.sjtu.edu.cn (Postfix) with ESMTPSA id 220EA200C02C4; Fri, 15 Oct 2021 15:36:17 +0800 (CST) Message-ID: <6772c5ef-4666-e2b5-2885-797baa939b45@sjtu.edu.cn> Date: Fri, 15 Oct 2021 15:36:17 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.2 Subject: Re: Antw: [EXT] Re: [PATCH] scsi scsi_transport_iscsi.c: fix misuse of %llu in scsi_transport_iscsi.c Content-Language: en-US To: Mike Christie , Ulrich Windl , jejb@linux.ibm.com, martin.petersen@oracle.com, Chris Leech , Lee Duncan Cc: open-iscsi , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org References: <20211009030254.205714-1-qtxuning1999@sjtu.edu.cn> <5daf69b365e23ceecee911c4d0f2f66a0b9ec95c.camel@perches.com> <6163DB2E020000A1000445F1@gwsmtp.uni-regensburg.de> From: Guo Zhi In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/10/11 23:29, Mike Christie wrote: > On 10/11/21 1:35 AM, Ulrich Windl wrote: >>>>> Joe Perches schrieb am 09.10.2021 um 05:14 in Nachricht >> <5daf69b365e23ceecee911c4d0f2f66a0b9ec95c.camel@perches.com>: >>> On Sat, 2021-10-09 at 11:02 +0800, Guo Zhi wrote: >>>> Pointers should be printed with %p or %px rather than >>>> cast to (unsigned long long) and printed with %llu. >>>> Change %llu to %p to print the pointer into sysfs. >>> ][] >>>> diff --git a/drivers/scsi/scsi_transport_iscsi.c >>> b/drivers/scsi/scsi_transport_iscsi.c >>> [] >>>> @@ -129,8 +129,8 @@ show_transport_handle(struct device *dev, struct >>> device_attribute *attr, >>>> >>>> >>>> if (!capable(CAP_SYS_ADMIN)) >>>> return -EACCES; >>>> - return sysfs_emit(buf, "%llu\n", >>>> - (unsigned long long)iscsi_handle(priv->iscsi_transport)); >>>> + return sysfs_emit(buf, "%p\n", >>>> + iscsi_ptr(priv->iscsi_transport)); >>> iscsi_transport is a pointer isn't it? >>> >>> so why not just >>> >>> return sysfs_emit(buf, "%p\n", priv->iscsi_transport); >> Isn't the difference that %p outputs hex, while %u outputs decimal? >> > Yeah, I think this patch will break userspace, because it doesn't know it's > a pointer. It could be doing: > > sscanf(str, "%llu", &val); > > The value is just later passed back to the kernel to look up a driver in > iscsi_if_transport_lookup: > > list_for_each_entry(priv, &iscsi_transports, list) { > if (tt == priv->iscsi_transport) { > > so we could just replace priv->transport with an int and use an ida to assign > the value. Taking security into consideration, We should not print kernel pointer into sysfs. However if this is a special pointer to lookup a driver,  It's really tricky for me to fix it, as I don't have a scsi device to test my code. Guo