From patchwork Thu Mar 19 21:43:04 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: 11448127 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 6BA8514B4 for ; Thu, 19 Mar 2020 22:07:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4AEF02076E for ; Thu, 19 Mar 2020 22:07:36 +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="f6XQ7p3E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727331AbgCSWHf (ORCPT ); Thu, 19 Mar 2020 18:07:35 -0400 Received: from gateway32.websitewelcome.com ([192.185.145.123]:20626 "EHLO gateway32.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727324AbgCSWHf (ORCPT ); Thu, 19 Mar 2020 18:07:35 -0400 X-Greylist: delayed 1468 seconds by postgrey-1.27 at vger.kernel.org; Thu, 19 Mar 2020 18:07:34 EDT Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway32.websitewelcome.com (Postfix) with ESMTP id 37405D119D for ; Thu, 19 Mar 2020 16:43:06 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id F2wUjjqQ8AGTXF2wUj9msK; Thu, 19 Mar 2020 16:43:06 -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=FvguBj7rVJCiKrPfcdD/dDqw8uFuJmmKDVRcEBgRUyQ=; b=f6XQ7p3EhpbYzqwn7v3WGBqjBS WPEkJQXYP0/V26HS5TeRAt3Ht0fR9dGJNjP7DwBsRtunv1DpzGc8PlkfSrqZw74U6TEyeUyBv9nku Ji3gwdAM7t6sFV7EvB5IcrsLtnJErsUs3N3JmAZn4jjs11aT3bv2MKDuX3xodoXhGTSuEc5LOsEPu u4C4mvm7SVbiP/27SLETZzups77Q2Qd4nAuTGxosgeNWHdo4vyzXrdUCf1Lv1DAv4FViqzyWyInml QOWtQO4ACTqA96NEasMctOlc3R22IModA653LsuvUg5LPXQ5Evu7mfNpfcJ6QiyETzdbhrWXPYZbM O/JZez4g==; Received: from cablelink-189-218-116-241.hosts.intercable.net ([189.218.116.241]:53376 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jF2wS-001jjo-Ms; Thu, 19 Mar 2020 16:43:04 -0500 Date: Thu, 19 Mar 2020 16:43:04 -0500 From: "Gustavo A. R. Silva" To: Dmitry Torokhov Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] input: keyboard: applespi: Replace zero-length array with flexible-array member Message-ID: <20200319214304.GA19987@embeddedor.com> 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: 189.218.116.241 X-Source-L: No X-Exim-ID: 1jF2wS-001jjo-Ms X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cablelink-189-218-116-241.hosts.intercable.net (embeddedor) [189.218.116.241]:53376 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 49 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-input-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-input@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/input/keyboard/applespi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/input/keyboard/applespi.c b/drivers/input/keyboard/applespi.c index d38398526965..14362ebab9a9 100644 --- a/drivers/input/keyboard/applespi.c +++ b/drivers/input/keyboard/applespi.c @@ -186,7 +186,7 @@ struct touchpad_protocol { u8 number_of_fingers; u8 clicked2; u8 unknown3[16]; - struct tp_finger fingers[0]; + struct tp_finger fingers[]; }; /**