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=-7.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 DA60AC64E8A for ; Wed, 2 Dec 2020 13:38:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89365221FB for ; Wed, 2 Dec 2020 13:38:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728064AbgLBNiG (ORCPT ); Wed, 2 Dec 2020 08:38:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34650 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727861AbgLBNiF (ORCPT ); Wed, 2 Dec 2020 08:38:05 -0500 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0421FC0613CF; Wed, 2 Dec 2020 05:37:25 -0800 (PST) Received: by mail-wr1-x444.google.com with SMTP id 23so3952285wrc.8; Wed, 02 Dec 2020 05:37:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=l/C90f3+rH95i4xGnwc1KHGWZKMjt7nbaW6VsSOdvrc=; b=u12vLg7+aWh9JsuOUB9vDnzS/ivy4SZwBk6Dil6rEpUw+6qqlzJ1tN5h15TNpe60AI FQM8O+u2hfu6Aaxvqi/oi8m39en3wd9fxk//keg5t4Hl/lZ4gnEjM131JIgEsu8yE5GL m8LO4Uw/eBaDRexUzrtM6YqtjT7K6E4ySHmosJRu4lYRM0NnwzRdkZpu2qHXoOwWTgSu lF4LhWR1HaxuUuOhORv1uiBB64b2zUEpN18ZtE2gpKnDamfQv74fO5H1DclKf98Wr6UE bwhMAlVEFOOFC/ePVcpmsuyd731OR7BvEgvN53X1pKFkWFDkE7oUj4/xWN5CXm35XPA1 Db9A== 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; bh=l/C90f3+rH95i4xGnwc1KHGWZKMjt7nbaW6VsSOdvrc=; b=kyR8usRZ49xGD6cqp/Jzdy5G+kO6SfmtDl+kcIZxjDqRu/aEi20UU5imMFwMepxr4I qk9J8oClLGKL6z1vtGVhFw6PwhPi2Ji6zaFzs/97XSjDz63TkHNuMcI3tBNvc6hZjTJG gmskgUOxA21UtIl5ID66+tPiEVVQVEAayoQr95s1YX/58X6CkI7Bn3dTqmI1J47ZZviy fSTRkN2Vl/F5IBufjxRD5MXBzLYelRT4Yv2xNe/hsKsNmsihY4Gzl+2FlC41V1tW5GOL kq5AavJppcgA5ppSjJukwWdDU3ku8i522RUiq0wv2acLMMCAetV5ZSEjfFMhEBDIBq5/ 9q3Q== X-Gm-Message-State: AOAM530aF7NtcyU6zy0StCqNzPIPWHFbdudK7Wb0M1odpHVSRjOZKdgu beDefbYAWbOZjsItLr5X5MVmNgpZeQsz7Q== X-Google-Smtp-Source: ABdhPJzAli4egIF1EuIcfm4bEgoLc58noXEvlENm2/2eRAT2Bwdb4BWXfqIMb6Ga8pFsgND+6WiZxA== X-Received: by 2002:adf:e80b:: with SMTP id o11mr3626633wrm.409.1606916243505; Wed, 02 Dec 2020 05:37:23 -0800 (PST) Received: from andrea (host-95-239-64-30.retail.telecomitalia.it. [95.239.64.30]) by smtp.gmail.com with ESMTPSA id q12sm2051316wrx.86.2020.12.02.05.37.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Dec 2020 05:37:23 -0800 (PST) Date: Wed, 2 Dec 2020 14:37:16 +0100 From: Andrea Parri To: Wei Liu Cc: 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: <20201202133716.GA22763@andrea> References: <20201202092214.13520-1-parri.andrea@gmail.com> <20201202092214.13520-3-parri.andrea@gmail.com> <20201202122254.zjhu3cfcq3zwvmvu@liuwe-devbox-debian-v2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201202122254.zjhu3cfcq3zwvmvu@liuwe-devbox-debian-v2> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > @@ -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. Andrea