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,URIBL_BLOCKED, 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 B6B59C433EF for ; Tue, 21 Sep 2021 00:31:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93BED600D4 for ; Tue, 21 Sep 2021 00:31:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233101AbhIUAdH (ORCPT ); Mon, 20 Sep 2021 20:33:07 -0400 Received: from gateway30.websitewelcome.com ([192.185.193.11]:43529 "EHLO gateway30.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230220AbhIUAbH (ORCPT ); Mon, 20 Sep 2021 20:31:07 -0400 X-Greylist: delayed 1327 seconds by postgrey-1.27 at vger.kernel.org; Mon, 20 Sep 2021 20:31:06 EDT Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway30.websitewelcome.com (Postfix) with ESMTP id A7BF896A1 for ; Mon, 20 Sep 2021 19:07:30 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id STJqmzDeFHlR1STJqmQXIJ; Mon, 20 Sep 2021 19:07:30 -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=OD4JC5dtfAt335bNgwNunS9YrQ3MNpy44kfHABxRQ6o=; b=iH6LhrBzbmbr/EZb1kGa+IQXkD 0eSrjYHNtkzmpF+dd6X6ZB/hImNDBSTVCvlcfujKW/3VnrE6VFWT4DPr0iqNn3uIqYgf6XE2Ibsgm lIE3fQ0sdEKlqWYArxjBEu3y3tbLaseh92xrStdwAg1dwpYFSthYdH9gZK2sa48bueC+8fXx/Ahmh BsWfsgu9PKx0Jgv1nFcR2PPfmyuI7xe9BvhI1BDSHr5QJ2FvgUGqawKjLFRrirr+6+5KkHwA80cao j3LJSn0dbFNjZdma8pSzxVQheVPsnB6S8iZac2hEpGx3SrvvOz2VF1nTLTNbCYHcdBXQzE1zjHSKE bL03eMsQ==; Received: from 187-162-31-110.static.axtel.net ([187.162.31.110]:33914 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 1mSTJq-000gZd-6d; Mon, 20 Sep 2021 19:07:30 -0500 Subject: Re: [PATCH] aio: Prefer struct_size over open coded arithmetic To: Len Baker , Benjamin LaHaise , Alexander Viro Cc: Kees Cook , "Gustavo A. R. Silva" , linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210919094539.30589-1-len.baker@gmx.com> From: "Gustavo A. R. Silva" Message-ID: <6cd35222-cc17-b3f5-dad4-ed540e0df79b@embeddedor.com> Date: Mon, 20 Sep 2021 19:11:17 -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: <20210919094539.30589-1-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: 1mSTJq-000gZd-6d 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]:33914 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 26 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On 9/19/21 04:45, 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, use the struct_size() helper to do the arithmetic instead of the > argument "size + size * count" 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 Reviewed-by: Gustavo A. R. Silva Thanks -- Gustavo > --- > fs/aio.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/fs/aio.c b/fs/aio.c > index 51b08ab01dff..c2978c0b872c 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -659,8 +659,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm) > new_nr = (table ? table->nr : 1) * 4; > spin_unlock(&mm->ioctx_lock); > > - table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) * > - new_nr, GFP_KERNEL); > + table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL); > if (!table) > return -ENOMEM; > > -- > 2.25.1 >