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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 ADFE9C433E0 for ; Fri, 19 Mar 2021 08:23:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 572E464F6D for ; Fri, 19 Mar 2021 08:23:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234225AbhCSIWq (ORCPT ); Fri, 19 Mar 2021 04:22:46 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:14402 "EHLO szxga06-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233819AbhCSIWZ (ORCPT ); Fri, 19 Mar 2021 04:22:25 -0400 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4F1xfk6Gfhzkc5D; Fri, 19 Mar 2021 16:20:46 +0800 (CST) Received: from [10.174.179.92] (10.174.179.92) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.498.0; Fri, 19 Mar 2021 16:22:15 +0800 Subject: Re: [PATCH 2/3] scsi: only copy data to user when the whole result is good To: Hannes Reinecke , , , , , , , , CC: References: <20210319030128.1345061-1-yanaijie@huawei.com> <20210319030128.1345061-3-yanaijie@huawei.com> <7279b268-0b57-c78a-b189-75e1515c7166@suse.de> From: Jason Yan Message-ID: Date: Fri, 19 Mar 2021 16:22:15 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <7279b268-0b57-c78a-b189-75e1515c7166@suse.de> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.92] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi Hannes, 在 2021/3/19 15:56, Hannes Reinecke 写道: > On 3/19/21 4:01 AM, Jason Yan wrote: >> When the scsi device status is offline, mode sense command will return a >> result with only DID_NO_CONNECT set. Then in sg_scsi_ioctl(), >> only status byte of the result is checked, and because of >> bug [1], garbage data is copied to the userspace. >> >> Only copy the buffer to userspace when the whole result is good. >> >> [1] >> https://patchwork.kernel.org/project/linux-block/patch/20210318122621.330010-1-yanaijie@huawei.com/ >> >> >> Signed-off-by: Jason Yan >> --- >>   block/scsi_ioctl.c | 2 +- >>   1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c >> index 6599bac0a78c..359bf0003af4 100644 >> --- a/block/scsi_ioctl.c >> +++ b/block/scsi_ioctl.c >> @@ -503,7 +503,7 @@ int sg_scsi_ioctl(struct request_queue *q, struct >> gendisk *disk, fmode_t mode, >>               if (copy_to_user(sic->data, req->sense, bytes)) >>                   err = -EFAULT; >>           } >> -    } else { >> +    } else if (scsi_result_is_good(req->result)) { >>           if (copy_to_user(sic->data, buffer, out_len)) >>               err = -EFAULT; >>       } >> > Hmm. Not sure about this one. > The prime motivator behind sg is to get _precisely_ all flags of the > command, and not do in-kernel error handling. > So one could argue that this behaviour is intentional, and would break > existing use-cases. > Thanks for the review. The existing usersapce can do nothing with the uninitialized data. Or the driver or disk may fill some data and at the same time set host_byte or driver_byte to non-zero? I'm not sure about this. And the return value of sg_scsi_ioctl() just get the status byte(only 8 bit), how can the users know about this situation? Thanks, Jason > Doug? > > Cheers, > > Hannes