From patchwork Mon Feb 17 19:58:16 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: 11387547 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 C3E2092A for ; Mon, 17 Feb 2020 20:17:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2D132070B for ; Mon, 17 Feb 2020 20:17:06 +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="rNPCQnyo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729661AbgBQURG (ORCPT ); Mon, 17 Feb 2020 15:17:06 -0500 Received: from gateway30.websitewelcome.com ([192.185.160.12]:20697 "EHLO gateway30.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728558AbgBQURF (ORCPT ); Mon, 17 Feb 2020 15:17:05 -0500 X-Greylist: delayed 1287 seconds by postgrey-1.27 at vger.kernel.org; Mon, 17 Feb 2020 15:17:04 EST Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway30.websitewelcome.com (Postfix) with ESMTP id 67E10133C for ; Mon, 17 Feb 2020 13:55:36 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 3mUSjttsgAGTX3mUSj53lN; Mon, 17 Feb 2020 13:55:36 -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=crsZaVbHNmz9iNAH8JjIvtOy8euRMhiayEMBT2tKPSA=; b=rNPCQnyoGNxrnnhTyp1ahn8zhf Fl6T1a8oHvVIdwFb4MkmEDJDTOpGcxPI3NsgLLtu+lwnbvJ/9mCYT1kBZ7rD2Rfm6pM8DHmkc2HX/ ffYzv/JaQKCKt4//9bSAuOQM9IrId4qWzgUT+PGBrFeNfdv4c5QHWxFR+WT/DE4BgC4ErlhHqYwFZ cxKsOCeFrLAK8hC8QUdu170I46KcFfddFaSl76R122Cq/xU49oliP3yBT2iH07pq3ktvIL7c8BAec QoOYasX33PJgk1g2S244DK3NKewDmtRx2SHSHFzZmPcQx1Q1bCoQzIeZma7o31mVxJcqLn3OIEIQY 7mSu22lg==; Received: from [200.68.140.26] (port=23204 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j3mUQ-000LJn-QK; Mon, 17 Feb 2020 13:55:34 -0600 Date: Mon, 17 Feb 2020 13:58:16 -0600 From: "Gustavo A. R. Silva" To: "David S. Miller" Cc: linux-usb@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH net-next] net: usb: cdc-phonet: Replace zero-length array with flexible-array member Message-ID: <20200217195816.GA3306@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: 200.68.140.26 X-Source-L: No X-Exim-ID: 1j3mUQ-000LJn-QK X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.68.140.26]:23204 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 16 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@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/net/usb/cdc-phonet.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/usb/cdc-phonet.c b/drivers/net/usb/cdc-phonet.c index bcabd39d136a..9bdbd7b472a0 100644 --- a/drivers/net/usb/cdc-phonet.c +++ b/drivers/net/usb/cdc-phonet.c @@ -36,7 +36,7 @@ struct usbpn_dev { spinlock_t rx_lock; struct sk_buff *rx_skb; - struct urb *urbs[0]; + struct urb *urbs[]; }; static void tx_complete(struct urb *req);