From patchwork Wed Feb 12 19:30:19 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: 11379113 X-Patchwork-Delegate: marcel@holtmann.org 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 6BA1B1395 for ; Wed, 12 Feb 2020 19:50:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47BC024689 for ; Wed, 12 Feb 2020 19:50:40 +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="ZFX5J109" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729091AbgBLTuj (ORCPT ); Wed, 12 Feb 2020 14:50:39 -0500 Received: from gateway34.websitewelcome.com ([192.185.148.142]:28603 "EHLO gateway34.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727439AbgBLTuj (ORCPT ); Wed, 12 Feb 2020 14:50:39 -0500 X-Greylist: delayed 1371 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Feb 2020 14:50:38 EST Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway34.websitewelcome.com (Postfix) with ESMTP id 66725CC3DF for ; Wed, 12 Feb 2020 13:27:46 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 1xfmjcqCtSl8q1xfmjLbj2; Wed, 12 Feb 2020 13:27:46 -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=cXVVVZahdCREnDttxEPWWOQJmnDqogHhZzVkeyWG2aw=; b=ZFX5J1092d9sXY15O402Wqynw5 jAnEzwJo/vD1J7w+VciAy0jPtfrMvvQlFLtHGBwV/8QEpRmbeHNvy60VE5e/V1fkMi6Ofx84Nx+zt kaNOmWgn/JSO0QK8/WV7hDaBkjIlszSTqgzQ4wTD1j+CQFjcWFpFMwqYMjZHR/Z34fP9YXylf2TxW kvpTW+pHlYytl058H7zc1TvWkdJwLC8GV704krajCaTT0DTUWbyckQw5k/ijKtGt69JNHRZcBoFXW Q4NgMDxW+3Enos+NZOEHLL/S4o3w27I7IDLweZFWwNByHiWmWasYhKRMLbuiPMj480Q2JlMiHPZhP W7pE4fFQ==; Received: from [201.144.174.25] (port=2142 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j1xfk-0015wx-Hq; Wed, 12 Feb 2020 13:27:44 -0600 Date: Wed, 12 Feb 2020 13:30:19 -0600 From: "Gustavo A. R. Silva" To: Marcel Holtmann , Johan Hedberg Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] Bluetooth: hci_uart: Replace zero-length array with flexible-array member Message-ID: <20200212193019.GA26196@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: 201.144.174.25 X-Source-L: No X-Exim-ID: 1j1xfk-0015wx-Hq X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.144.174.25]:2142 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 11 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@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 inadvertenly 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/bluetooth/hci_ag6xx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/bluetooth/hci_ag6xx.c b/drivers/bluetooth/hci_ag6xx.c index 8bafa650b5b0..1f55df93e4ce 100644 --- a/drivers/bluetooth/hci_ag6xx.c +++ b/drivers/bluetooth/hci_ag6xx.c @@ -27,7 +27,7 @@ struct ag6xx_data { struct pbn_entry { __le32 addr; __le32 plen; - __u8 data[0]; + __u8 data[]; } __packed; static int ag6xx_open(struct hci_uart *hu)