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=-13.0 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 16191C4332B for ; Fri, 20 Mar 2020 23:15:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5C9320739 for ; Fri, 20 Mar 2020 23:15:47 +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="eC9Lo3RO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727303AbgCTXPq (ORCPT ); Fri, 20 Mar 2020 19:15:46 -0400 Received: from gateway20.websitewelcome.com ([192.185.47.18]:22181 "EHLO gateway20.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727092AbgCTXPq (ORCPT ); Fri, 20 Mar 2020 19:15:46 -0400 Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway20.websitewelcome.com (Postfix) with ESMTP id D925E400D18E0 for ; Fri, 20 Mar 2020 17:00:12 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id FQrgjdtCWEfyqFQrgjdfF8; Fri, 20 Mar 2020 18:15:44 -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=3Z1WXMUOzv6vhoMjbWqc+zBYP+E1MZRZuQ59FW4vRVo=; b=eC9Lo3ROEAZr9wxU6R57O+U2Ma 3mG5p21GiDyzx+UhjWA75sTEzGjXvIdR6g59CK7+/4TLdmlpPIcdHgLgUi1NUzxu0+4bhlToCWUDT X+lSbopPDyARR9wPwmXiKAIYOkDS4QJH/098YNbvduBSt8lKyUyHEgOu4sRHaKuj2q0jBjVb0E3/H dIT6H09ZUEKpXya56J8QYQoulHVQif7N/CU/jhED7VCPDTlWroflcFjDPJkmE10Gq4gFz+jqYltcv 2I1+GetiTc8VJkUEY6+3iEihgnMwZR0zd9ywdxcnTwv2Wds5WrvYugIYwxX7sweskMe94qHD3/iUM s6kbBfNw==; Received: from cablelink-189-218-116-241.hosts.intercable.net ([189.218.116.241]:53572 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jFQrf-001IEP-27; Fri, 20 Mar 2020 18:15:43 -0500 Date: Fri, 20 Mar 2020 18:15:42 -0500 From: "Gustavo A. R. Silva" To: Benson Leung , Enric Balletbo i Serra , Guenter Roeck Cc: linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] chrome: cros_ec_chardev: Replace zero-length array with flexible-array member Message-ID: <20200320231542.GA19872@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: 1jFQrf-001IEP-27 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cablelink-189-218-116-241.hosts.intercable.net (embeddedor) [189.218.116.241]:53572 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 13 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/platform/chrome/cros_ec_chardev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/platform/chrome/cros_ec_chardev.c b/drivers/platform/chrome/cros_ec_chardev.c index b51ab24055f3..e0bce869c49a 100644 --- a/drivers/platform/chrome/cros_ec_chardev.c +++ b/drivers/platform/chrome/cros_ec_chardev.c @@ -48,7 +48,7 @@ struct ec_event { struct list_head node; size_t size; u8 event_type; - u8 data[0]; + u8 data[]; }; static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen) -- 2.23.0