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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 4B305C5ACCC for ; Thu, 18 Oct 2018 04:48:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F05E3208E4 for ; Thu, 18 Oct 2018 04:48:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F05E3208E4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=davemloft.net 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 S1727571AbeJRMrW (ORCPT ); Thu, 18 Oct 2018 08:47:22 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:54426 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727495AbeJRMrW (ORCPT ); Thu, 18 Oct 2018 08:47:22 -0400 Received: from localhost (c-67-183-62-245.hsd1.wa.comcast.net [67.183.62.245]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id D979913AE1397; Wed, 17 Oct 2018 21:48:17 -0700 (PDT) Date: Wed, 17 Oct 2018 21:48:17 -0700 (PDT) Message-Id: <20181017.214817.899061946206965862.davem@davemloft.net> To: gustavo@embeddedor.com Cc: netanel@amazon.com, saeedb@amazon.com, zorik@amazon.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next] net: ena: fix unintended sign extension From: David Miller In-Reply-To: <20181012194948.GA24925@embeddedor.com> References: <20181012194948.GA24925@embeddedor.com> X-Mailer: Mew version 6.7 on Emacs 26 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Wed, 17 Oct 2018 21:48:18 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Gustavo A. R. Silva" Date: Fri, 12 Oct 2018 21:49:48 +0200 > In the following expression: > > 372 size = io_sq->bounce_buf_ctrl.buffer_size * > 373 io_sq->bounce_buf_ctrl.buffers_num; > > both buffer_size and buffers_num are of type u16 (16 bits, unsigned), > so they are promoted to type int (32 bits, signed) and then > sign-extended to type size_t. > > Fix this by casting io_sq->bounce_buf_ctrl.buffer_size to size_t in > order to avoid the sign extension and unintended results. > > Addresses-Coverity-ID: 1474187 ("Unintended sign extension") > Addresses-Coverity-ID: 1474189 ("Unintended sign extension") > Fixes: 689b2bdaaa14 ("net: ena: add functions for handling Low Latency Queues in ena_com") > Signed-off-by: Gustavo A. R. Silva I don't understand how this can possibly be a real problem, and it looks therefore like we are just papering over a coverity warning. I'm not applying this without more information and justification.