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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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=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 036F8C433F5 for ; Mon, 20 Sep 2021 23:55:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6B8560F6E for ; Mon, 20 Sep 2021 23:55:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237112AbhITX4x (ORCPT ); Mon, 20 Sep 2021 19:56:53 -0400 Received: from gateway24.websitewelcome.com ([192.185.51.196]:29840 "EHLO gateway24.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239850AbhITXyx (ORCPT ); Mon, 20 Sep 2021 19:54:53 -0400 Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway24.websitewelcome.com (Postfix) with ESMTP id 3A7B718D1 for ; Mon, 20 Sep 2021 18:53:24 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id ST6Cmz27mHlR1ST6CmQLko; Mon, 20 Sep 2021 18:53:24 -0500 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=embeddedor.com; s=default; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=9dKrNFiIoQV/+gE4BwQR5jmTOuHAiTPni8wW5D6aAnw=; b=cdVSmnaDElW698bbPVn0JtIKyf gE92q9CxgK48XjHTjzj0tT4urlocEEFLNJCrL/p+SrAu5yLIuWpZkRd1aXGaXkDCv/lr4j8mo0Kar edZhkIfGJ45lpzKJTJ4sjCKgi//nuVY9PhVs7Pm8kiJZPvCWE3I9oB/Ml3bWp906I2ei9X+r6104M cGD4fEBPxky90cZrwmarkSfsqM65AZkt2Qj6G8ykeCq0J76mQzLds0h9FOH83UMFcOXXBhDEzEu9U ef0aEemZKD+J+lZb0i5JsvW8ETSq1aOyxxLsY8Zv5SD+cCjbfJcyV67Pci6QeSd0GKcj1w1cV9AHI pHQjx/Og==; Received: from 187-162-31-110.static.axtel.net ([187.162.31.110]:33600 helo=[192.168.15.9]) by gator4166.hostgator.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1mST6B-000NEv-NP; Mon, 20 Sep 2021 18:53:23 -0500 Subject: Re: [PATCH] scsi: advansys: Prefer struct_size over open coded arithmetic To: Len Baker , Matthew Wilcox , Hannes Reinecke , "James E.J. Bottomley" , "Martin K. Petersen" Cc: "Gustavo A. R. Silva" , Kees Cook , linux-hardening@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210918111805.15471-1-len.baker@gmx.com> From: "Gustavo A. R. Silva" Message-ID: <422fbbe3-6f22-b16d-7af2-23efeb6dd125@embeddedor.com> Date: Mon, 20 Sep 2021 18:57:06 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210918111805.15471-1-len.baker@gmx.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 187.162.31.110 X-Source-L: No X-Exim-ID: 1mST6B-000NEv-NP X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: 187-162-31-110.static.axtel.net ([192.168.15.9]) [187.162.31.110]:33600 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 9 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 9/18/21 06:18, Len Baker wrote: > As noted in the "Deprecated Interfaces, Language Features, Attributes, > and Conventions" documentation [1], size calculations (especially > multiplication) should not be performed in memory allocator (or similar) > function arguments due to the risk of them overflowing. This could lead > to values wrapping around and a smaller allocation being made than the > caller was expecting. Using those allocations could lead to linear > overflows of heap memory and other misbehaviors. > > So, refactor the code a bit to use the struct_size() helper instead of > the argument "size + count * size" in the kzalloc() function. > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker > --- > drivers/scsi/advansys.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c > index ffb391967573..fe882502e7bf 100644 > --- a/drivers/scsi/advansys.c > +++ b/drivers/scsi/advansys.c > @@ -7465,6 +7465,7 @@ static int asc_build_req(struct asc_board *boardp, struct scsi_cmnd *scp, > return ASC_BUSY; > } else if (use_sg > 0) { > int sgcnt; > + size_t size; I don't think a new variable is needed. > struct scatterlist *slp; > struct asc_sg_head *asc_sg_head; > > @@ -7477,8 +7478,8 @@ static int asc_build_req(struct asc_board *boardp, struct scsi_cmnd *scp, > return ASC_ERROR; > } > > - asc_sg_head = kzalloc(sizeof(asc_scsi_q->sg_head) + > - use_sg * sizeof(struct asc_sg_list), GFP_ATOMIC); > + size = struct_size(asc_scsi_q->sg_head, sg_list, use_sg); > + asc_sg_head = kzalloc(size, GFP_ATOMIC); You can go with this: diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c index ffb391967573..e341b3372482 100644 --- a/drivers/scsi/advansys.c +++ b/drivers/scsi/advansys.c @@ -7477,8 +7477,8 @@ static int asc_build_req(struct asc_board *boardp, struct scsi_cmnd *scp, return ASC_ERROR; } - asc_sg_head = kzalloc(sizeof(asc_scsi_q->sg_head) + - use_sg * sizeof(struct asc_sg_list), GFP_ATOMIC); + asc_sg_head = kzalloc(struct_size(asc_sg_head, sg_list, use_sg), + GFP_ATOMIC); if (!asc_sg_head) { scsi_dma_unmap(scp); set_host_byte(scp, DID_SOFT_ERROR); It perfectly fits withing the 80 columns, which by the way is deprecated but still good-to-have. Also, if you are finding these instances with the help of Coccinelle, it'd be nice if you mention that in the changelog text. :) Thanks! -- Gustavo > if (!asc_sg_head) { > scsi_dma_unmap(scp); > set_host_byte(scp, DID_SOFT_ERROR); > -- > 2.25.1 >