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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 21858C433FE for ; Sun, 6 Dec 2020 18:21:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D6C2E2311B for ; Sun, 6 Dec 2020 18:21:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726602AbgLFSVX (ORCPT ); Sun, 6 Dec 2020 13:21:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726318AbgLFSVX (ORCPT ); Sun, 6 Dec 2020 13:21:23 -0500 Received: from mail-wm1-x342.google.com (mail-wm1-x342.google.com [IPv6:2a00:1450:4864:20::342]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EEBA6C0613D1; Sun, 6 Dec 2020 10:20:42 -0800 (PST) Received: by mail-wm1-x342.google.com with SMTP id c198so9675951wmd.0; Sun, 06 Dec 2020 10:20:42 -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=IBlcf7ksAuEvCZLcbkUIbzhFbCOYIpwbh1pRZSUCoh8=; b=CcQXNj1wsGNheX+8oj+t/QWoZ/AuEQVIzeh8fal/2XbOaP/cXtrWyZ44uOgkd+/J6M gf1UyIRJLPXax2V62Qz9zcfaSTSmJ6lojyCAjN8EF3q1o8dax769eMwMcjSDBs2BOBAQ YJEr3lQBSuXZznBZ7hik1M8i/+1YIF1hwLB6azAppGHP0boatQ9RqLa7YiAl+p584kGN eWt2FS47kLC3t+0gLXnil+Y3PM49XK1pSE6FBl35nXrYiMyGvA6iJMW7RUEi/uKdW+mM L0QgFtBZS7YGhMeA2XL+/N9avd0XezpTJLKhiRixIbRJ71ol7I6x4RtO0il7CFjRJG6u U5MA== 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=IBlcf7ksAuEvCZLcbkUIbzhFbCOYIpwbh1pRZSUCoh8=; b=EatOL2ZbKTQZpYy/LVV+VJ8PpKOzZS8fu+8x++Bq8cGUGYrmpE4341Tw7Lq1V4NzPO YVrG2fxBWKMwTVhktXr2hC700BmkQuio0mglWtj1yZkE85MeOWwAv8xdvi2l28NysOSl J1+6nEBHGOnG+Oz8Dt5PIMCA9z8vcyWFsmFDuwdWrdiNnl3r+BFAvJYaDD+HeR8xsQF8 9bRT6gwMQV37VRFGWFDN8cTaRSDSYe7OktS/2PKElMmYJ7rKIV753YSQaR7SKOLrq5Fg X/iwXDcKfMiZyM3XFifOhxD091XxarQQdDzyX8bjDWfKgfMyTg+DlRG/aU3hvkFwj8Lc 316A== X-Gm-Message-State: AOAM530Xht/PZk3kBilVnvseL9Fko9GS403hZCCxcCz2CsRnilRO11Ku ZZs57Q/uVFI5BCQno9l0Q1XEWKj9mcBqsQ== X-Google-Smtp-Source: ABdhPJxpNxmkFxPV6UQxlH7Yhs0kXZrOeoAiv8LD6C6kaXJHvAVt+4NS8fEvfDLeoqivW4AgQ9+RXw== X-Received: by 2002:a7b:c8da:: with SMTP id f26mr15235508wml.155.1607278841449; Sun, 06 Dec 2020 10:20:41 -0800 (PST) Received: from andrea (host-95-239-64-30.retail.telecomitalia.it. [95.239.64.30]) by smtp.gmail.com with ESMTPSA id b200sm11369891wmb.10.2020.12.06.10.20.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Dec 2020 10:20:41 -0800 (PST) Date: Sun, 6 Dec 2020 19:20:38 +0100 From: Andrea Parri To: Michael Kelley Cc: "linux-kernel@vger.kernel.org" , KY Srinivasan , Haiyang Zhang , Stephen Hemminger , Wei Liu , "linux-hyperv@vger.kernel.org" , Juan Vazquez , Saruhan Karademir Subject: Re: [PATCH 3/6] Drivers: hv: vmbus: Avoid double fetch of payload_size in vmbus_on_msg_dpc() Message-ID: <20201206182038.GC3256@andrea> References: <20201118143649.108465-1-parri.andrea@gmail.com> <20201118143649.108465-4-parri.andrea@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Sun, Dec 06, 2020 at 05:14:18PM +0000, Michael Kelley wrote: > From: Andrea Parri (Microsoft) Sent: Wednesday, November 18, 2020 6:37 AM > > > > vmbus_on_msg_dpc() double fetches from payload_size. The double fetch > > can lead to a buffer overflow when (mem)copying the hv_message object. > > Avoid the double fetch by saving the value of payload_size into a local > > variable. > > Similar comment here about providing some brief context in the commit > message on the problem that we are guarding against by removing the > double fetch. Will expand. > > I could see combining this patch with the previous one since the > motivation and pattern of the changes are exactly the same, just for > two different fields. Will consider this suggestion for v3. Please see v2 for a related discussion. Andrea