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,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 5A8B1C35656 for ; Fri, 21 Feb 2020 15:37:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DC84206E2 for ; Fri, 21 Feb 2020 15:37:42 +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="Xyhucb8T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728441AbgBUPhk (ORCPT ); Fri, 21 Feb 2020 10:37:40 -0500 Received: from gateway20.websitewelcome.com ([192.185.46.107]:31521 "EHLO gateway20.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727053AbgBUPhk (ORCPT ); Fri, 21 Feb 2020 10:37:40 -0500 Received: from cm12.websitewelcome.com (cm12.websitewelcome.com [100.42.49.8]) by gateway20.websitewelcome.com (Postfix) with ESMTP id 3C591400ED3DA for ; Fri, 21 Feb 2020 08:20:30 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 5AK2jR7buvBMd5AK2jNzoC; Fri, 21 Feb 2020 09:34:34 -0600 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=GKpPXo3AQzEVA4yK0J3aDuF9U4AWBQfi0jCw2uWOJA8=; b=Xyhucb8TPqtTHYPTm2KwEZzI9v 45aburvxF5dgGvB7X/qjNl/CI03acT8Ulf3aZRD9UXd8WVUFurj4/CkeWrhVD8/9Y6xeLlKDxZZSB UTWifZN/qWkO6EIo1Sj3SX8ab7l4vO34ZfRMxyqGxjJReS6FUmJJzX+YuqPQvcVu929mFuZI+bCcb m/dgRBnVx0AUA6/3ArS1P6uAmPJSxAm9CLJioK6KrFGSaz7a7kqD2pZFHk5gKjtammRf+bZw9JFav xzJ1N2xp3G12T06yef4KVb0Qiv2EAQ3AO0xmcxBvxURNAjTs2/W2lApFMK5o1LjB4Dmlc61mlqSNe YOtTsfpg==; Received: from [200.68.140.54] (port=28252 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j5AJy-003jkr-Vk; Fri, 21 Feb 2020 09:34:32 -0600 Date: Fri, 21 Feb 2020 09:37:13 -0600 From: "Gustavo A. R. Silva" To: Khalid Aziz Cc: linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] pcdp: Replace zero-length array with flexible-array member Message-ID: <20200221153713.GA23760@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: 200.68.140.54 X-Source-L: No X-Exim-ID: 1j5AJy-003jkr-Vk X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.68.140.54]:28252 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 21 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/firmware/pcdp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firmware/pcdp.h b/drivers/firmware/pcdp.h index ce75d1da9e84..e02540571c52 100644 --- a/drivers/firmware/pcdp.h +++ b/drivers/firmware/pcdp.h @@ -103,6 +103,6 @@ struct pcdp { u8 creator_id[4]; u32 creator_rev; u32 num_uarts; - struct pcdp_uart uart[0]; /* actual size is num_uarts */ + struct pcdp_uart uart[]; /* actual size is num_uarts */ /* remainder of table is pcdp_device structures */ } __attribute__((packed)); -- 2.25.0