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 7E85BC4332D for ; Thu, 19 Mar 2020 21:18:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 55B092072C for ; Thu, 19 Mar 2020 21:18:53 +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="HmiGlcHJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727195AbgCSVSw (ORCPT ); Thu, 19 Mar 2020 17:18:52 -0400 Received: from gateway31.websitewelcome.com ([192.185.144.91]:44259 "EHLO gateway31.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726680AbgCSVSv (ORCPT ); Thu, 19 Mar 2020 17:18:51 -0400 Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway31.websitewelcome.com (Postfix) with ESMTP id 977944BDB8 for ; Thu, 19 Mar 2020 16:18:50 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id F2Z0jKmnZXVkQF2Z0jbtkd; Thu, 19 Mar 2020 16:18:50 -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=r5HlPDuxrsVXq6VYWoARvW6vv4oS/EL6J5+Kn6lcldI=; b=HmiGlcHJOCXxibJhbEpBYCZuOU XlmDMFfA65klqMKVDFyjbugbNhR+LkFJIBiv9nAR5jmgF+AW4B9mjlm8IsSjY8mJqRtZ+Xwcq9qpR 1pnFo4Z1OfDpn+Y/bLE3qK973IBB/Qtt48XN+m7TuEZwAo0M+0xnhR7+nlOL67v5QRCaNCkFrQHUG fCOi6L8wTPWNfOsL/ez/w/IGUXKpVop+QlbCRn1adx0PFEOyshriSTmkob9bOc1Rwkj7bhO/gKUdG TCcxieHeM9Fgh65ZJd0bx1dSDapvBONs3TWDq8fSi6xXFVb1KGW5IlL6jpiUQcr2IdKCFFIx3fUbz +W2x95tg==; Received: from cablelink-189-218-116-241.hosts.intercable.net ([189.218.116.241]:53240 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jF2Yz-001WoO-2M; Thu, 19 Mar 2020 16:18:49 -0500 Date: Thu, 19 Mar 2020 16:18:48 -0500 From: "Gustavo A. R. Silva" To: Stefan Richter Cc: linux1394-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] firewire: core-transaction: Replace zero-length array with flexible-array member Message-ID: <20200319211848.GA3252@embeddedor.com> 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: 189.218.116.241 X-Source-L: No X-Exim-ID: 1jF2Yz-001WoO-2M X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cablelink-189-218-116-241.hosts.intercable.net (embeddedor) [189.218.116.241]:53240 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 8 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 --- drivers/firewire/core-transaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c index 404a035f104d..439d918bbaaf 100644 --- a/drivers/firewire/core-transaction.c +++ b/drivers/firewire/core-transaction.c @@ -620,7 +620,7 @@ struct fw_request { u32 request_header[4]; int ack; u32 length; - u32 data[0]; + u32 data[]; }; static void free_response_callback(struct fw_packet *packet, -- 2.23.0