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=-15.5 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, 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 DB6C3C83013 for ; Wed, 2 Dec 2020 12:23:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 500F82224A for ; Wed, 2 Dec 2020 12:23:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729904AbgLBMXp (ORCPT ); Wed, 2 Dec 2020 07:23:45 -0500 Received: from mail-wr1-f68.google.com ([209.85.221.68]:33755 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726066AbgLBMXo (ORCPT ); Wed, 2 Dec 2020 07:23:44 -0500 Received: by mail-wr1-f68.google.com with SMTP id u12so3723039wrt.0; Wed, 02 Dec 2020 04:23:22 -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=p9yZnJwUyGYJWXufZN6mWISbIVmm/nLFQLYOSV6Egd8=; b=JW7PUlZXGi8+MUpZeRe6f4wkIqyvrAbgO5iNVIP5Ozg3qZb0vK/XrZupLF7hm1moPD Cg7QoLlRNkXOh6CWrOOnoUy88mjnEvift6LhN6svRkDVKse+A+JLY9IbN+UhuaXemPNk JGDfNB19T3uebZ1w32Cn7buhU6E9qR+RxV+/5yoTKxuDMdhoJra9hJLZXPMNvXmxekrU DDcxohc0swI8qkeUI5qsMUv86YreEE8+aHR0XzW5Op3AqINElJR2fGUc51a9GesQc4Fg C001R+NNjBQN2b8LdwTbKEBHYpbG8whY7GdoKEsazh/+GAhZJ7K1dakRncezF/DS3Jz2 RoiA== X-Gm-Message-State: AOAM531fILkcvtZKufd3/tzugW3KULCaCpUiCenrGnWwRkDiOupmC9uT 1ZVuaGufhLLJclTcp2GAbD8= X-Google-Smtp-Source: ABdhPJzaap45vwcn7+2rJjslwsNC5S8s9IkkvW3wnhHWpU6oLLly8GMf8Sh94X8BcJKXhfKYx6dXmw== X-Received: by 2002:adf:e787:: with SMTP id n7mr3176959wrm.153.1606911776720; Wed, 02 Dec 2020 04:22:56 -0800 (PST) Received: from liuwe-devbox-debian-v2 ([51.145.34.42]) by smtp.gmail.com with ESMTPSA id g78sm1814572wme.33.2020.12.02.04.22.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Dec 2020 04:22:56 -0800 (PST) Date: Wed, 2 Dec 2020 12:22:54 +0000 From: Wei Liu To: "Andrea Parri (Microsoft)" Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, "K . Y . Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , 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: <20201202122254.zjhu3cfcq3zwvmvu@liuwe-devbox-debian-v2> References: <20201202092214.13520-1-parri.andrea@gmail.com> <20201202092214.13520-3-parri.andrea@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201202092214.13520-3-parri.andrea@gmail.com> User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 02, 2020 at 10:22:09AM +0100, Andrea Parri (Microsoft) wrote: > vmbus_on_msg_dpc() double fetches from msgtype. The double fetch can > lead to an out-of-bound access when accessing the channel_message_table > array. In turn, the use of the out-of-bound entry could lead to code > execution primitive (entry->message_handler()). Avoid the double fetch > by saving the value of msgtype into a local variable. > > Reported-by: Juan Vazquez > Signed-off-by: Andrea Parri (Microsoft) > --- > drivers/hv/vmbus_drv.c | 18 +++++++++++++----- > 1 file changed, 13 insertions(+), 5 deletions(-) > > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c > index 0a2711aa63a15..82b23baa446d7 100644 > --- a/drivers/hv/vmbus_drv.c > +++ b/drivers/hv/vmbus_drv.c > @@ -1057,6 +1057,7 @@ void vmbus_on_msg_dpc(unsigned long data) > struct hv_message *msg = (struct hv_message *)page_addr + > VMBUS_MESSAGE_SINT; > struct vmbus_channel_message_header *hdr; > + enum vmbus_channel_message_type msgtype; > const struct vmbus_channel_message_table_entry *entry; > struct onmessage_work_context *ctx; > u32 message_type = msg->header.message_type; > @@ -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? Wei.