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 A0CA5C10F27 for ; Mon, 9 Mar 2020 18:07:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6B98E20578 for ; Mon, 9 Mar 2020 18:07:01 +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="OR94NR7d" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727334AbgCISHA (ORCPT ); Mon, 9 Mar 2020 14:07:00 -0400 Received: from gateway24.websitewelcome.com ([192.185.51.196]:47911 "EHLO gateway24.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726269AbgCISHA (ORCPT ); Mon, 9 Mar 2020 14:07:00 -0400 Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway24.websitewelcome.com (Postfix) with ESMTP id C366C3D08FD for ; Mon, 9 Mar 2020 13:06:58 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id BMnqjWd4gAGTXBMnqjyPKX; Mon, 09 Mar 2020 13:06:58 -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: Cc:To:From:Date:Sender:Reply-To: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=Vb54cLSvPsXKWYl9Uu3Xdo1u6mHlzTCiMBQVMibC31E=; b=OR94NR7dX+CIJD1BT73j8FaZBI 779HwshMroI13BfyDG1CDrPKpJGHNVVxElzNT6EaqFafdoIpTzZT4yqL2jQ+MMJ3Nb3IE0uUAwCQF NvicACmxb7YKu6WO3nh76UfqPc5D9iZcRQss2vn/rqNFqqqcVWBWujx7krXRwmXWs/K4s7qZryNNf eKVzeATxW/YPwheUvb4uM+QEO9u14nTrMDwrN4S+UPfe7TSurbFrMVIJfScPsXqvmw88CWbeRiXeZ V8i5j5U8QaRJFnuHiWCk7WZupg4HnJ8TSnefMlmOwRuYBvnlDwJyQbNqKCDOyIneYfshz5PCSz1Xk u5RWEgvA==; Received: from [201.162.240.150] (port=23942 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jBMno-004DyT-8u; Mon, 09 Mar 2020 13:06:56 -0500 Date: Mon, 9 Mar 2020 13:10:08 -0500 From: "Gustavo A. R. Silva" To: Jaegeuk Kim , Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] f2fs: xattr.h: Replace zero-length array with flexible-array member Message-ID: <20200309181008.GA3537@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: 1jBMno-004DyT-8u X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.162.240.150]:23942 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 11 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/f2fs/xattr.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/f2fs/xattr.h b/fs/f2fs/xattr.h index de0c600b9cab..95d589bf8e22 100644 --- a/fs/f2fs/xattr.h +++ b/fs/f2fs/xattr.h @@ -49,7 +49,7 @@ struct f2fs_xattr_entry { __u8 e_name_index; __u8 e_name_len; __le16 e_value_size; /* size of attribute value */ - char e_name[0]; /* attribute name */ + char e_name[]; /* attribute name */ }; #define XATTR_HDR(ptr) ((struct f2fs_xattr_header *)(ptr)) -- 2.25.0