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=-10.5 required=3.0 tests=BAYES_00,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 979B9C64E7C for ; Wed, 2 Dec 2020 13:41:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BBCA221FB for ; Wed, 2 Dec 2020 13:41:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730209AbgLBNks (ORCPT ); Wed, 2 Dec 2020 08:40:48 -0500 Received: from mail-wr1-f68.google.com ([209.85.221.68]:34480 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730190AbgLBNks (ORCPT ); Wed, 2 Dec 2020 08:40:48 -0500 Received: by mail-wr1-f68.google.com with SMTP id k14so4018063wrn.1; Wed, 02 Dec 2020 05:40:32 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=E2aHvC6gzDfI13t0gWtopdzCEI0eCcmet0QIX5R7nH4=; b=FAAHdyDDdfwTbkVV40baCdZHh0PAbtT9ZIp+Fi1tTNSLQG5JWbsimCOhLglWF2dp0c LqBae5QhRancBYofoUbvMD8h60mtUNAkC3ZvS1lSIn6T66LGCOzTYgMOMkjSdhrlwYoj H2lOmxYaClQNQ3Qv76rZRsAnqyCOu5LM4ojGCZj2P8g/4piRUdREag5aqNKiH9sz6yLe 1Knpl6NYuhKzYe8y46pCJp5lIVZkAgViqFkgdOm2YZETgJC3L6GYYgAmsEelz3hncU98 ZhjZHTgDoI9FewPlOd/AvUgaPX5TDXcwo+QxY3MMEf+SEjv5AsVZmXftkqgwVYcAXPpE p3eg== X-Gm-Message-State: AOAM533SracTavbr20gu7Q2TfLH0FstVSXCvkxCtHEz7mTO1eUogX7J6 Kyqit9Sm2Bn6S5ryLKFyqbiJZ4tF7QQ= X-Google-Smtp-Source: ABdhPJwSEdEnNoMwjSB5do+eY/S6NR33quyCHC5uvvq8xOcxvE3w0/81V39yPD3u7hjPYniwZPxMQQ== X-Received: by 2002:adf:8b4a:: with SMTP id v10mr3571804wra.212.1606916406345; Wed, 02 Dec 2020 05:40:06 -0800 (PST) Received: from liuwe-devbox-debian-v2 ([51.145.34.42]) by smtp.gmail.com with ESMTPSA id f3sm2144514wrx.10.2020.12.02.05.40.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Dec 2020 05:40:05 -0800 (PST) Date: Wed, 2 Dec 2020 13:40:04 +0000 From: Wei Liu To: Andrea Parri Cc: Wei Liu , linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, "K . Y . Srinivasan" , Haiyang Zhang , Stephen Hemminger , Michael Kelley , Juan Vazquez , Saruhan Karademir Subject: Re: [PATCH v2 2/7] Drivers: hv: vmbus: Avoid double fetch of msgtype in vmbus_on_msg_dpc() Message-ID: <20201202134004.5tgrbyijrhvwwmk2@liuwe-devbox-debian-v2> References: <20201202092214.13520-1-parri.andrea@gmail.com> <20201202092214.13520-3-parri.andrea@gmail.com> <20201202122254.zjhu3cfcq3zwvmvu@liuwe-devbox-debian-v2> <20201202133716.GA22763@andrea> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201202133716.GA22763@andrea> User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 02, 2020 at 02:37:16PM +0100, Andrea Parri wrote: > > > @@ -1072,12 +1073,19 @@ void vmbus_on_msg_dpc(unsigned long data) > > > /* no msg */ > > > return; > > > > > > + /* > > > + * The hv_message object is in memory shared with the host. The host > > > + * could erroneously or maliciously modify such object. Make sure to > > > + * validate its fields and avoid double fetches whenever feasible. > > > + */ > > > + > > > hdr = (struct vmbus_channel_message_header *)msg->u.payload; > > > + msgtype = hdr->msgtype; > > > > Should READ_ONCE be used here? > > I think it should. Thank you for pointing this out. Glad I can help. The same comment applies to other patches as well, of course. Wei. > > Andrea