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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:36580 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kclul-0007LZ-3Z for qemu-devel@archiver.kernel.org; Wed, 11 Nov 2020 03:55:39 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:40888) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kcltq-0006SH-1F for qemu-devel@nongnu.org; Wed, 11 Nov 2020 03:54:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:40086) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kcltm-0004sT-2O for qemu-devel@nongnu.org; Wed, 11 Nov 2020 03:54:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605084876; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3cckyKckgoj/EA7ZhQK2oPX0BE2/Uar+Cc7I9jZ2Cu4=; b=AJ0cj2qq6agaNirXa5yarMy1HUi4sNI3LRXJEK43vnEtZUh5UhmJXl0/R9VjKOvHpLFzPF wd2UumpvIbBUOZO4d7FzjH/bDvZGh1cwChfB69sdv3kNTsk6/6R6KTqfbRq0Bw+ndLNUdY o7lvx/rg0GqKtBj54BPEaIT+9u2qBg0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-412-bhq_zzkjNUeX4yFCzvd05A-1; Wed, 11 Nov 2020 03:54:32 -0500 X-MC-Unique: bhq_zzkjNUeX4yFCzvd05A-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9C6291084C83; Wed, 11 Nov 2020 08:54:31 +0000 (UTC) Received: from [10.72.12.213] (ovpn-12-213.pek2.redhat.com [10.72.12.213]) by smtp.corp.redhat.com (Postfix) with ESMTP id E63915E1DD; Wed, 11 Nov 2020 08:54:28 +0000 (UTC) Subject: Re: [PATCH] net/e1000e_core: make sure RDH never exceeds RDT in e1000e_ring_advance() To: Mauro Matteo Cascella References: <20201105105616.327593-1-mcascell@redhat.com> From: Jason Wang Message-ID: Date: Wed, 11 Nov 2020 16:54:24 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jasowang@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Received-SPF: pass client-ip=63.128.21.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/11 01:42:46 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: gaoning.pgn@antgroup.com, 330cjfdn@gmail.com, Dmitry Fleytman , Laszlo Ersek , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2020/11/10 下午5:06, Mauro Matteo Cascella wrote: > On Mon, Nov 9, 2020 at 3:38 AM Jason Wang wrote: >> >> On 2020/11/5 下午6:56, Mauro Matteo Cascella wrote: >>> The e1000e_write_packet_to_guest() function iterates over a set of >>> receive descriptors by advancing rx descriptor head register (RDH) from >>> its initial value to rx descriptor tail register (RDT). The check in >>> e1000e_ring_empty() is responsible for detecting whether RDH has reached >>> RDT, terminating the loop if that's the case. Additional checks have >>> been added in the past to deal with bogus values submitted by the guest >>> to prevent possible infinite loop. This is done by "wrapping around" RDH >>> at some point and detecting whether it assumes the original value during >>> the loop. >>> >>> However, when e1000e is configured to use the packet split feature, RDH is >>> incremented by two instead of one, as the packet split descriptors are >>> 32 bytes while regular descriptors are 16 bytes. A malicious or buggy >>> guest may set RDT to an odd value and transmit only null RX descriptors. >>> This corner case would prevent RDH from ever matching RDT, leading to an >>> infinite loop. This patch adds a check in e1000e_ring_advance() to make >>> sure RDH does never exceed RDT. >>> >>> This issue was independently reported by Gaoning Pan (Zhejiang University) >>> and Cheolwoo Myung. >>> >>> Signed-off-by: Mauro Matteo Cascella >>> Reported-by: Gaoning Pan >>> Reported-by: Cheolwoo Myung <330cjfdn@gmail.com> >>> --- >>> References: >>> https://git.qemu.org/?p=qemu.git;a=commit;h=dd793a74882477ca38d49e191110c17dfe >>> https://git.qemu.org/?p=qemu.git;a=commit;h=4154c7e03fa55b4cf52509a83d50d6c09d743b7 >>> http://www.intel.com/content/dam/doc/datasheet/82574l-gbe-controller-datasheet.pdf >>> >>> hw/net/e1000e_core.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c >>> index bcd186cac5..4c4d14b6ed 100644 >>> --- a/hw/net/e1000e_core.c >>> +++ b/hw/net/e1000e_core.c >>> @@ -831,6 +831,10 @@ e1000e_ring_advance(E1000ECore *core, const E1000E_RingInfo *r, uint32_t count) >>> { >>> core->mac[r->dh] += count; >>> >>> + if (core->mac[r->dh] > core->mac[r->dt]) { >>> + core->mac[r->dh] = core->mac[r->dt]; >>> + } >>> + >>> if (core->mac[r->dh] * E1000_RING_DESC_LEN >= core->mac[r->dlen]) { >>> core->mac[r->dh] = 0; >>> } > Hi Jason, > >> A question here. >> >> When count > 1, is this correct to reset dh here? >> >> Thanks >> > My understanding is that wrapping at (or above) RDLEN is the correct > behavior regardless of count. I don't see why count > 1 should modify > this behavior. I'm not sure, though. Anyway, this patch fixes the > above reproducer, so I'm adding a Tested-by line here. > > Tested-by: Mauro Matteo Cascella > > Thank you, > -- > Mauro Matteo Cascella > Red Hat Product Security > PGP-Key ID: BB3410B0 > Right. Applied. Thanks