From nobody Sun Nov 24 23:20:04 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1720108747092698.3005488428669; Thu, 4 Jul 2024 08:59:07 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sPOlt-0000RX-A4; Thu, 04 Jul 2024 11:53:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sPOlg-0000Dq-KW; Thu, 04 Jul 2024 11:53:08 -0400 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sPOlb-0001zk-44; Thu, 04 Jul 2024 11:53:07 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 6212377490; Thu, 4 Jul 2024 18:52:46 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id 2A574FEADB; Thu, 4 Jul 2024 18:52:51 +0300 (MSK) Received: (nullmailer pid 1481674 invoked by uid 1000); Thu, 04 Jul 2024 15:52:51 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Alexey Dobriyan , Jason Wang , Michael Tokarev Subject: [Stable-8.2.6 02/18] virtio-net: drop too short packets early Date: Thu, 4 Jul 2024 18:52:33 +0300 Message-Id: <20240704155251.1481617-2-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1720108748940100001 Content-Type: text/plain; charset="utf-8" From: Alexey Dobriyan Reproducer from https://gitlab.com/qemu-project/qemu/-/issues/1451 creates small packet (1 segment, len =3D 10 =3D=3D n->guest_hdr_len), then destroys queue. "if (n->host_hdr_len !=3D n->guest_hdr_len)" is triggered, if body creates zero length/zero segment packet as there is nothing after guest header. qemu_sendv_packet_async() tries to send it. slirp discards it because it is smaller than Ethernet header, but returns 0 because tx hooks are supposed to return total length of data. 0 is propagated upwards and is interpreted as "packet has been sent" which is terrible because queue is being destroyed, nobody is waiting for TX to complete and assert it triggered. Fix is discard such empty packets instead of sending them. Length 1 packets will go via different codepath: virtqueue_push(q->tx_vq, elem, 0); virtio_notify(vdev, q->tx_vq); g_free(elem); and aren't problematic. Signed-off-by: Alexey Dobriyan Signed-off-by: Jason Wang (cherry picked from commit 2c3e4e2de699cd4d9f6c71f30a22d8f125cd6164) Signed-off-by: Michael Tokarev diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 8451dbee41..0467b3bd8a 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -2709,18 +2709,14 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *= q) out_sg =3D elem->out_sg; if (out_num < 1) { virtio_error(vdev, "virtio-net header not in first element"); - virtqueue_detach_element(q->tx_vq, elem, 0); - g_free(elem); - return -EINVAL; + goto detach; } =20 if (n->has_vnet_hdr) { if (iov_to_buf(out_sg, out_num, 0, &vhdr, n->guest_hdr_len) < n->guest_hdr_len) { virtio_error(vdev, "virtio-net header incorrect"); - virtqueue_detach_element(q->tx_vq, elem, 0); - g_free(elem); - return -EINVAL; + goto detach; } if (n->needs_vnet_hdr_swap) { virtio_net_hdr_swap(vdev, (void *) &vhdr); @@ -2751,6 +2747,11 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) n->guest_hdr_len, -1); out_num =3D sg_num; out_sg =3D sg; + + if (out_num < 1) { + virtio_error(vdev, "virtio-net nothing to send"); + goto detach; + } } =20 ret =3D qemu_sendv_packet_async(qemu_get_subqueue(n->nic, queue_in= dex), @@ -2771,6 +2772,11 @@ drop: } } return num_packets; + +detach: + virtqueue_detach_element(q->tx_vq, elem, 0); + g_free(elem); + return -EINVAL; } =20 static void virtio_net_tx_timer(void *opaque); --=20 2.39.2