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=-13.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 B405EC38A24 for ; Thu, 7 May 2020 18:48:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8933824956 for ; Thu, 7 May 2020 18:48:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588877306; bh=4UwgB4pEdhhDwE0Vi3P7TXaWRto19eGF34jli3AKVNU=; h=Date:From:To:Cc:Subject:List-ID:From; b=Dmm3N4+I1iSa1J3xsoP0oA3Nr4VJz/wjzTrhXRO/4LYIT4dwHVgEHriZ/Sh42Mzi1 lwQ7Hi95S32dTM2moK6pGD4AbNZy7J1/WOnx2aSSa1t/0wRj5eHvbjpH+Dh5CBM+j1 knnJShUZ6qwN3CwONVzYOoEvUk0fx46ehSGtBWK0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728593AbgEGSsZ (ORCPT ); Thu, 7 May 2020 14:48:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:49338 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728110AbgEGSsZ (ORCPT ); Thu, 7 May 2020 14:48:25 -0400 Received: from embeddedor (unknown [189.207.59.248]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3705121BE5; Thu, 7 May 2020 18:48:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588877304; bh=4UwgB4pEdhhDwE0Vi3P7TXaWRto19eGF34jli3AKVNU=; h=Date:From:To:Cc:Subject:From; b=BFatDpXiYufb1iEB9KedA/kbpUg3ymmg4Z8Toa/K6ebGqNZQCYlUI0pm0zXDGt1UZ pIiVC0gj8ZUOLMfXY5ka9AfMdjP6+yxY44k+GMITgoDdHX2EzOvSVJi3FUoqlhaOsJ AFQVDBp4K88/MzM6HqsFckcb2xjq62RerQQpb72Q= Date: Thu, 7 May 2020 13:52:51 -0500 From: "Gustavo A. R. Silva" To: Stefan Richter Cc: linux1394-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: [PATCH] firewire: ohci: Replace zero-length array with flexible-array Message-ID: <20200507185251.GA14293@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) 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] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. 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/firewire/core-cdev.c | 2 +- drivers/firewire/core-transaction.c | 2 +- drivers/firewire/core.h | 2 +- drivers/firewire/nosy.c | 2 +- drivers/firewire/ohci.c | 2 +- 5 files changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c index 6e291d8f3a27..e6fc20dff687 100644 --- a/drivers/firewire/core-cdev.c +++ b/drivers/firewire/core-cdev.c @@ -117,7 +117,7 @@ struct inbound_transaction_resource { struct descriptor_resource { struct client_resource resource; struct fw_descriptor descriptor; - u32 data[0]; + u32 data[]; }; struct iso_resource { diff --git a/drivers/firewire/core-transaction.c b/drivers/firewire/core-transaction.c index 404a035f104d..439d918bbaaf 100644 --- a/drivers/firewire/core-transaction.c +++ b/drivers/firewire/core-transaction.c @@ -620,7 +620,7 @@ struct fw_request { u32 request_header[4]; int ack; u32 length; - u32 data[0]; + u32 data[]; }; static void free_response_callback(struct fw_packet *packet, diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h index 4b0e4ee655a1..71d5f16f311c 100644 --- a/drivers/firewire/core.h +++ b/drivers/firewire/core.h @@ -191,7 +191,7 @@ struct fw_node { /* Upper layer specific data. */ void *data; - struct fw_node *ports[0]; + struct fw_node *ports[]; }; static inline struct fw_node *fw_node_get(struct fw_node *node) diff --git a/drivers/firewire/nosy.c b/drivers/firewire/nosy.c index 6ca2f5ab6c57..5fd6a60b6741 100644 --- a/drivers/firewire/nosy.c +++ b/drivers/firewire/nosy.c @@ -52,7 +52,7 @@ struct pcl { struct packet { unsigned int length; - char data[0]; + char data[]; }; struct packet_buffer { diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index 33269316f111..54fdc39cd0bc 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -111,7 +111,7 @@ struct descriptor_buffer { dma_addr_t buffer_bus; size_t buffer_size; size_t used; - struct descriptor buffer[0]; + struct descriptor buffer[]; }; struct context {