From patchwork Fri Feb 21 16:00:05 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 11396821 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BD96313A4 for ; Fri, 21 Feb 2020 16:18:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B5E72073A for ; Fri, 21 Feb 2020 16:18:50 +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="FhvXqQUt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727312AbgBUQSu (ORCPT ); Fri, 21 Feb 2020 11:18:50 -0500 Received: from gateway30.websitewelcome.com ([50.116.127.1]:14123 "EHLO gateway30.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727213AbgBUQSt (ORCPT ); Fri, 21 Feb 2020 11:18:49 -0500 X-Greylist: delayed 1287 seconds by postgrey-1.27 at vger.kernel.org; Fri, 21 Feb 2020 11:18:49 EST Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway30.websitewelcome.com (Postfix) with ESMTP id 2247D1CA3A for ; Fri, 21 Feb 2020 09:57:22 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 5Ag6jWUTBAGTX5Ag6jgrx6; Fri, 21 Feb 2020 09:57:22 -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=WtMzr2gjoX6df0EoQz24CcYsj+i/bg0u7qsVYdxv5ak=; b=FhvXqQUtu/kbV+Vrnk71BG8yZl 0TSU2YZiZPuLm929TonrbWh+9w4cqnRMB47gz6qXSDLBweYpn9jQ+EjXxYW/M5bcxnogAtcQqyQcT d9YOOfhiTjG1h/fi3IibqqqRun0NUq+ZHlwKQZa8WF1W2O438fbUpOSn0SFF5xQGz3i5HQoQ0UFmX 1o4m7QN23g9FgLM7f75UPYJm5fMx6rIzxCe4Df7P2QFM8aOXA9Ml7jH9RJH7sBkjxlO1tdJ73WDIu G/2bBwvnZdm9s6uI2vLVmlN8cuWvlEiicixYHyVO2UPgWMqlvYp+ALBiFytrjN6JVHyz9MPmuV3z3 EJXGFXrQ==; Received: from [200.68.140.54] (port=6638 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j5Ag4-003vD4-K4; Fri, 21 Feb 2020 09:57:20 -0600 Date: Fri, 21 Feb 2020 10:00:05 -0600 From: "Gustavo A. R. Silva" To: Bartlomiej Zolnierkiewicz Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] video: Replace zero-length array with flexible-array member Message-ID: <20200221160005.GA13552@embeddedor> MIME-Version: 1.0 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: 1j5Ag4-003vD4-K4 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.68.140.54]:6638 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 31 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@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/video/fbdev/mmp/hw/mmp_ctrl.h | 2 +- drivers/video/fbdev/ssd1307fb.c | 2 +- include/video/mmp_disp.h | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/video/fbdev/mmp/hw/mmp_ctrl.h b/drivers/video/fbdev/mmp/hw/mmp_ctrl.h index 335d4983dc52..167585a889d3 100644 --- a/drivers/video/fbdev/mmp/hw/mmp_ctrl.h +++ b/drivers/video/fbdev/mmp/hw/mmp_ctrl.h @@ -1406,7 +1406,7 @@ struct mmphw_ctrl { /*pathes*/ int path_num; - struct mmphw_path_plat path_plats[0]; + struct mmphw_path_plat path_plats[]; }; static inline int overlay_is_vid(struct mmp_overlay *overlay) diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c index 142535267fec..fb2640fe575a 100644 --- a/drivers/video/fbdev/ssd1307fb.c +++ b/drivers/video/fbdev/ssd1307fb.c @@ -89,7 +89,7 @@ struct ssd1307fb_par { struct ssd1307fb_array { u8 type; - u8 data[0]; + u8 data[]; }; static const struct fb_fix_screeninfo ssd1307fb_fix = { diff --git a/include/video/mmp_disp.h b/include/video/mmp_disp.h index 1f9bc133e230..77252cb46361 100644 --- a/include/video/mmp_disp.h +++ b/include/video/mmp_disp.h @@ -231,7 +231,7 @@ struct mmp_path { /* layers */ int overlay_num; - struct mmp_overlay overlays[0]; + struct mmp_overlay overlays[]; }; extern struct mmp_path *mmp_get_path(const char *name);