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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=ham 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 9F865C282C4 for ; Mon, 4 Feb 2019 10:52:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6E9362070C for ; Mon, 4 Feb 2019 10:52:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549277557; bh=/ODgW+Ivz4QTZGpGzpE3lb1baENgVju05+6ky6HV5r8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZFoXPDNItUM0HAFrvRRTEXDGP42hCkqhFj5I7wB6aJimsfZWjLKQ/skVNa62nbOLh EQogNDhyI0YYc4PJUEuaFb40T8vsqkLRN43qkGtIHk//zysjk5dxOH6eniJ5CF2Gtf AZ3w2bvzrt6lxeYJ+JxToqIKhsxPdEyr6qcWZj/k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732215AbfBDKwf (ORCPT ); Mon, 4 Feb 2019 05:52:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:50150 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731981AbfBDKwa (ORCPT ); Mon, 4 Feb 2019 05:52:30 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A3A1C217D6; Mon, 4 Feb 2019 10:52:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549277549; bh=/ODgW+Ivz4QTZGpGzpE3lb1baENgVju05+6ky6HV5r8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tvKfsH4L/HZGWdZX+W4oyrhNNiOOEdgvUgbC5CHzGHCyhOFo9Xh/ADEX5Mc3Ih4eC 1FVJve8lOJKbUhGlaYtPYLHB2Yd+lF4j4rlt91ytpL0DS0e+1+RwaefxMLoeN6w0Cs U09eIIhoYTeVEQftTzb1pPO8j5mpWxtyfaR8iK/g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Toshiaki Makita , Jason Wang , "Michael S. Tsirkin" , "David S. Miller" Subject: [PATCH 4.20 31/80] virtio_net: Dont process redirected XDP frames when XDP is disabled Date: Mon, 4 Feb 2019 11:36:51 +0100 Message-Id: <20190204103624.323212969@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190204103620.287366543@linuxfoundation.org> References: <20190204103620.287366543@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.20-stable review patch. If anyone has any objections, please let me know. ------------------ From: Toshiaki Makita [ Upstream commit 03aa6d34868c07b2b1b8b2db080602d7ec528173 ] Commit 8dcc5b0ab0ec ("virtio_net: fix ndo_xdp_xmit crash towards dev not ready for XDP") tried to avoid access to unexpected sq while XDP is disabled, but was not complete. There was a small window which causes out of bounds sq access in virtnet_xdp_xmit() while disabling XDP. An example case of - curr_queue_pairs = 6 (2 for SKB and 4 for XDP) - online_cpu_num = xdp_queue_paris = 4 when XDP is enabled: CPU 0 CPU 1 (Disabling XDP) (Processing redirected XDP frames) virtnet_xdp_xmit() virtnet_xdp_set() _virtnet_set_queues() set curr_queue_pairs (2) check if rq->xdp_prog is not NULL virtnet_xdp_sq(vi) qp = curr_queue_pairs - xdp_queue_pairs + smp_processor_id() = 2 - 4 + 1 = -1 sq = &vi->sq[qp] // out of bounds access set xdp_queue_pairs (0) rq->xdp_prog = NULL Basically we should not change curr_queue_pairs and xdp_queue_pairs while someone can read the values. Thus, when disabling XDP, assign NULL to rq->xdp_prog first, and wait for RCU grace period, then change xxx_queue_pairs. Note that we need to keep the current order when enabling XDP though. - v2: Make rcu_assign_pointer/synchronize_net conditional instead of _virtnet_set_queues. Fixes: 186b3c998c50 ("virtio-net: support XDP_REDIRECT") Signed-off-by: Toshiaki Makita Acked-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/virtio_net.c | 33 ++++++++++++++++++++++++++------- 1 file changed, 26 insertions(+), 7 deletions(-) --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2409,6 +2409,10 @@ static int virtnet_xdp_set(struct net_de return -ENOMEM; } + old_prog = rtnl_dereference(vi->rq[0].xdp_prog); + if (!prog && !old_prog) + return 0; + if (prog) { prog = bpf_prog_add(prog, vi->max_queue_pairs - 1); if (IS_ERR(prog)) @@ -2423,21 +2427,30 @@ static int virtnet_xdp_set(struct net_de } } + if (!prog) { + for (i = 0; i < vi->max_queue_pairs; i++) { + rcu_assign_pointer(vi->rq[i].xdp_prog, prog); + if (i == 0) + virtnet_restore_guest_offloads(vi); + } + synchronize_net(); + } + err = _virtnet_set_queues(vi, curr_qp + xdp_qp); if (err) goto err; netif_set_real_num_rx_queues(dev, curr_qp + xdp_qp); vi->xdp_queue_pairs = xdp_qp; - for (i = 0; i < vi->max_queue_pairs; i++) { - old_prog = rtnl_dereference(vi->rq[i].xdp_prog); - rcu_assign_pointer(vi->rq[i].xdp_prog, prog); - if (i == 0) { - if (!old_prog) + if (prog) { + for (i = 0; i < vi->max_queue_pairs; i++) { + rcu_assign_pointer(vi->rq[i].xdp_prog, prog); + if (i == 0 && !old_prog) virtnet_clear_guest_offloads(vi); - if (!prog) - virtnet_restore_guest_offloads(vi); } + } + + for (i = 0; i < vi->max_queue_pairs; i++) { if (old_prog) bpf_prog_put(old_prog); if (netif_running(dev)) { @@ -2450,6 +2463,12 @@ static int virtnet_xdp_set(struct net_de return 0; err: + if (!prog) { + virtnet_clear_guest_offloads(vi); + for (i = 0; i < vi->max_queue_pairs; i++) + rcu_assign_pointer(vi->rq[i].xdp_prog, old_prog); + } + if (netif_running(dev)) { for (i = 0; i < vi->max_queue_pairs; i++) { virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);