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=-13.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 8770FC10F27 for ; Mon, 9 Mar 2020 18:12:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6146D20578 for ; Mon, 9 Mar 2020 18:12:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=embeddedor.com header.i=@embeddedor.com header.b="UBOITjMP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727393AbgCISMZ (ORCPT ); Mon, 9 Mar 2020 14:12:25 -0400 Received: from gateway36.websitewelcome.com ([192.185.187.5]:19477 "EHLO gateway36.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726169AbgCISMY (ORCPT ); Mon, 9 Mar 2020 14:12:24 -0400 Received: from cm16.websitewelcome.com (cm16.websitewelcome.com [100.42.49.19]) by gateway36.websitewelcome.com (Postfix) with ESMTP id 54CC1400C8B41 for ; Mon, 9 Mar 2020 12:27:54 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id BMt6jLEUW8vkBBMt6jE66l; Mon, 09 Mar 2020 13:12:24 -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-Type:MIME-Version:Message-ID:Subject: To:From:Date:Sender:Reply-To:Cc:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=1BqnBgcIZWcdwyXyY58wkKDJ6z4EHF65kFVf0+SX/4w=; b=UBOITjMP3k/jvlJ5kjBGGWr3B2 UNwDEomSNJ1MOMY9++ZkkTeJklnYIbdJ1zy8nQPWqN0zaphfLTsZ34VeKesKuT91HzZSLfXZhAcDQ 1EMe4Zwm9Is+lH0v5zCAyeVbI4hQYS9rTJRZg8W6OPotRgXi14zAC0wFQPw5tI+zU1umuuPXfDk4O 2TW04y1iARAOoepNU96R1v2I8Rh4nCH4W/eyQSTActhVEHDyLZEoYFmZ+JdE83jhi0qCk+w6btzG7 2FGFDBTtprjpmE4dkKfoqSNm1KnW3O23zUaNTy2NJ4s0q+kIcFEhttL2j8xWWwlpgIDWxN6YI9Axo Prs3BUjg==; Received: from [201.162.240.150] (port=22004 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jBMt4-004GjZ-D5; Mon, 09 Mar 2020 13:12:23 -0500 Date: Mon, 9 Mar 2020 13:15:27 -0500 From: "Gustavo A. R. Silva" To: linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] isofs: rock.h: Replace zero-length array with flexible-array member Message-ID: <20200309181527.GA4134@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) 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: 201.162.240.150 X-Source-L: No X-Exim-ID: 1jBMt4-004GjZ-D5 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.162.240.150]:22004 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 16 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva --- fs/isofs/rock.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/isofs/rock.h b/fs/isofs/rock.h index 1558cf22ef8a..ee9660e9671c 100644 --- a/fs/isofs/rock.h +++ b/fs/isofs/rock.h @@ -22,7 +22,7 @@ struct SU_ER_s { __u8 len_des; __u8 len_src; __u8 ext_ver; - __u8 data[0]; + __u8 data[]; } __attribute__ ((packed)); struct RR_RR_s { @@ -44,7 +44,7 @@ struct RR_PN_s { struct SL_component { __u8 flags; __u8 len; - __u8 text[0]; + __u8 text[]; } __attribute__ ((packed)); struct RR_SL_s { @@ -54,7 +54,7 @@ struct RR_SL_s { struct RR_NM_s { __u8 flags; - char name[0]; + char name[]; } __attribute__ ((packed)); struct RR_CL_s { @@ -71,7 +71,7 @@ struct stamp { struct RR_TF_s { __u8 flags; - struct stamp times[0]; /* Variable number of these beasts */ + struct stamp times[]; /* Variable number of these beasts */ } __attribute__ ((packed)); /* Linux-specific extension for transparent decompression */ -- 2.25.0