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bh=hupWbg4zyTMMXDvwKczKsW0TJfmHBBcfoa9ppxyPO0g=; b=AC2vZ3IGQea/Qk9vepTV5qaNf+fjiu3bA73iOw5fjptdZxqKDCqALNeFfwBbRvV6i750tQ grA84p6szm7sfZKOQaR67y9r21dK/QmiLVWgY+rM2KzixkLr1A6bfiPq+s068tTx4wIVk5 SbuuK3FREUhehmD3PNJyGckdWGAMguw= 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-553-WxCEVboqOJGVFG_L5HhFCg-1; Wed, 24 Feb 2021 08:17:08 -0500 X-MC-Unique: WxCEVboqOJGVFG_L5HhFCg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6867A195D560; Wed, 24 Feb 2021 13:17:06 +0000 (UTC) Received: from wangxiaodeMacBook-Air.local (ovpn-12-168.pek2.redhat.com [10.72.12.168]) by smtp.corp.redhat.com (Postfix) with ESMTP id 065DA60C61; Wed, 24 Feb 2021 13:17:04 +0000 (UTC) Subject: Re: [PATCH 1/6] net: introduce qemu_receive_packet() To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org References: <20210224055401.492407-1-jasowang@redhat.com> <20210224055401.492407-2-jasowang@redhat.com> <9e432ff0-793e-64a7-97f3-ff3a374ee98f@redhat.com> From: Jason Wang Message-ID: Date: Wed, 24 Feb 2021 21:17:03 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <9e432ff0-793e-64a7-97f3-ff3a374ee98f@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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-GB Received-SPF: pass client-ip=216.205.24.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: QEMU Security , ppandit@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2021/2/24 6:11 下午, Philippe Mathieu-Daudé wrote: > On 2/24/21 6:53 AM, Jason Wang wrote: >> Some NIC supports loopback mode and this is done by calling >> nc->info->receive() directly which in fact suppresses the effort of >> reentrancy check that is done in qemu_net_queue_send(). >> >> Unfortunately we can use qemu_net_queue_send() here since for loop >> back there's no sender as peer, so this patch introduce a >> qemu_receive_packet() which is used for implementing loopback mode >> for a NIC with this check. > IIUC the guest could trigger an infinite loop and brick the emulated > device model. Likely exhausting the stack, so either SEGV by > corruption or some ENOMEM? Yes. > > Since this is guest triggerable, shouldn't we contact qemu-security@ > list and ask for a CVE for this issue, so distributions can track > the patches to backport in their stable releases? (it seems to be > within the KVM devices boundary). That's the plan. I discussed this with Prasad before and he promise to ask CVE for this. But it's a knwon issue, the reentrant DMA which has been discussed before[1], unfortuantely we don't make any progress. This patch can only fix the NIC RX issue. Thanks [1] https://mail.gnu.org/archive/html/qemu-devel/2020-09/msg00906.html > >> NIC that supports loopback mode will be converted to this helper. >> >> Signed-off-by: Jason Wang >> --- >> include/net/net.h | 5 +++++ >> include/net/queue.h | 8 ++++++++ >> net/net.c | 38 +++++++++++++++++++++++++++++++------- >> net/queue.c | 22 ++++++++++++++++++++++ >> 4 files changed, 66 insertions(+), 7 deletions(-)