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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 F37DEC43142 for ; Tue, 26 Jun 2018 07:21:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 81723265E0 for ; Tue, 26 Jun 2018 07:21:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 81723265E0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lip6.fr Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752561AbeFZHV5 (ORCPT ); Tue, 26 Jun 2018 03:21:57 -0400 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:28913 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751905AbeFZHVz (ORCPT ); Tue, 26 Jun 2018 03:21:55 -0400 X-IronPort-AV: E=Sophos;i="5.51,273,1526335200"; d="scan'208";a="333290168" Received: from dhcp-64-47.ens-lyon.fr ([140.77.64.47]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Jun 2018 09:21:52 +0200 Date: Tue, 26 Jun 2018 09:21:52 +0200 (CEST) From: Julia Lawall X-X-Sender: jll@hadrien To: Joe Perches cc: Chengguang Xu , jakub.kicinski@netronome.com, davem@davemloft.net, LKML , cocci , oss-drivers@netronome.com, netdev@vger.kernel.org, Dmitry Torokhov , linux-input , linux-s390 Subject: Re: [PATCH v2 net] nfp: cast sizeof() to int when comparing with error code In-Reply-To: Message-ID: References: <20180626011631.22717-1-cgxu519@gmx.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 25 Jun 2018, Joe Perches wrote: > On Tue, 2018-06-26 at 09:16 +0800, Chengguang Xu wrote: > > sizeof() will return unsigned value so in the error check > > negative error code will be always larger than sizeof(). > > This looks like a general class of error in the kernel > where a signed result that could be returning a -errno > is tested against < or <= sizeof() > > A couple examples: > > drivers/input/mouse/elan_i2c_smbus.c: > > len = i2c_smbus_read_block_data(client, > ETP_SMBUS_IAP_PASSWORD_READ, > val); > if (len < sizeof(u16)) { > > i2c_smbus_read_block_data can return a negative errno > > > net/smc/smc_clc.c: > > len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1, > sizeof(struct smc_clc_msg_decline)); > if (len < sizeof(struct smc_clc_msg_decline)) > > where kernel_sendmsg can return a negative errno > > There are probably others, I didn't look hard. > > Perhaps a cocci script to find these could be generated? Currently there is a rule for comparison of unsigneds to 0. It would be reasonable to extend it for sizes. I will see what it gives. julia