From patchwork Tue Mar 27 23:42:16 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dongli Zhang X-Patchwork-Id: 891864 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=oracle.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=oracle.com header.i=@oracle.com header.b="oX5EIhKW"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 409nbL1qqMz9s0b for ; Wed, 28 Mar 2018 10:41:34 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752643AbeC0XlW (ORCPT ); Tue, 27 Mar 2018 19:41:22 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:35030 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752525AbeC0XlV (ORCPT ); Tue, 27 Mar 2018 19:41:21 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w2RNTrVQ022377; Tue, 27 Mar 2018 23:41:17 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id; s=corp-2017-10-26; bh=8l8IDGmAxHo4PM1eR94sNzF8x4gqRcvoBKucDcpQPMo=; b=oX5EIhKW1d+EhyQaduLAfS2VrVMk7rVVfutRcBTG6Q76si282AB6VCfbvOz9xP3X5ogK 0qRmvZe5vomc0PnLYxmHmiOuc+sN/bWpNT4rvyViH4aOve5V2lzkTPAxmjYDknyzIQXX tN7MaEDu+GPSa2tZapch4t7L4Rk9SKAckT4XbeO5AIn7rzupYFWjBycNt2BGaPLUt7Dg /DO1BVKkO6HHTrHnfWVGWPX8cbmDvRBKSt380ezOlcxY4iS8fF+OtO6oT6fsdu37Hl1J gMZjVRuD6Jq5B91rk9dwFuh6ZpRqF04o0Uv1SVnIueis7vma33UuzRKsPbhSXL3VQAbM fg== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp2120.oracle.com with ESMTP id 2gyyp7g194-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 27 Mar 2018 23:41:17 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w2RNfFlI032454 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 27 Mar 2018 23:41:16 GMT Received: from abhmp0019.oracle.com (abhmp0019.oracle.com [141.146.116.25]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w2RNfFeF021159; Tue, 27 Mar 2018 23:41:15 GMT Received: from linux.cn.oracle.com (/10.182.69.93) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 27 Mar 2018 16:41:15 -0700 From: Dongli Zhang To: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org, wei.liu2@citrix.com, paul.durrant@citrix.com Subject: [PATCH 1/1] xen-netback: process malformed sk_buff correctly to avoid BUG_ON() Date: Wed, 28 Mar 2018 07:42:16 +0800 Message-Id: <1522194136-11985-1-git-send-email-dongli.zhang@oracle.com> X-Mailer: git-send-email 2.7.4 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8845 signatures=668695 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1803270232 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The "BUG_ON(!frag_iter)" in function xenvif_rx_next_chunk() is triggered if the received sk_buff is malformed, that is, when the sk_buff has pattern (skb->data_len && !skb_shinfo(skb)->nr_frags). Below is a sample call stack: [ 438.652658] ------------[ cut here ]------------ [ 438.652660] kernel BUG at drivers/net/xen-netback/rx.c:325! [ 438.652714] invalid opcode: 0000 [#1] SMP NOPTI [ 438.652813] CPU: 0 PID: 2492 Comm: vif1.0-q0-guest Tainted: G O 4.16.0-rc6+ #1 [ 438.652896] RIP: e030:xenvif_rx_skb+0x3c2/0x5e0 [xen_netback] [ 438.652926] RSP: e02b:ffffc90040877dc8 EFLAGS: 00010246 [ 438.652956] RAX: 0000000000000160 RBX: 0000000000000022 RCX: 0000000000000001 [ 438.652993] RDX: ffffc900402890d0 RSI: 0000000000000000 RDI: ffffc90040889000 [ 438.653029] RBP: ffff88002b460040 R08: ffffc90040877de0 R09: 0100000000000000 [ 438.653065] R10: 0000000000007ff0 R11: 0000000000000002 R12: ffffc90040889000 [ 438.653100] R13: ffffffff80000000 R14: 0000000000000022 R15: 0000000080000000 [ 438.653149] FS: 00007f15603778c0(0000) GS:ffff880030400000(0000) knlGS:0000000000000000 [ 438.653188] CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 438.653219] CR2: 0000000001832a08 CR3: 0000000029c12000 CR4: 0000000000042660 [ 438.653262] Call Trace: [ 438.653284] ? xen_hypercall_event_channel_op+0xa/0x20 [ 438.653313] xenvif_rx_action+0x41/0x80 [xen_netback] [ 438.653341] xenvif_kthread_guest_rx+0xb2/0x2a8 [xen_netback] [ 438.653374] ? __schedule+0x352/0x700 [ 438.653398] ? wait_woken+0x80/0x80 [ 438.653421] kthread+0xf3/0x130 [ 438.653442] ? xenvif_rx_action+0x80/0x80 [xen_netback] [ 438.653470] ? kthread_destroy_worker+0x40/0x40 [ 438.653497] ret_from_fork+0x35/0x40 The issue is hit by xen-netback when there is bug with other networking interface (e.g., dom0 physical NIC), who has generated and forwarded malformed sk_buff to dom0 vifX.Y. It is possible to reproduce the issue on purpose with below sample code in a kernel module: skb->dev = dev; // dev of vifX.Y skb->len = 386; skb->data_len = 352; skb->tail = 98; skb->end = 384; dev->netdev_ops->ndo_start_xmit(skb, dev); This patch stops processing sk_buff immediately if it is detected as malformed, that is, pkt->frag_iter is NULL but there is still remaining pkt->remaining_len. Signed-off-by: Dongli Zhang --- drivers/net/xen-netback/rx.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c index b1cf7c6..289cc82 100644 --- a/drivers/net/xen-netback/rx.c +++ b/drivers/net/xen-netback/rx.c @@ -369,6 +369,14 @@ static void xenvif_rx_data_slot(struct xenvif_queue *queue, offset += len; pkt->remaining_len -= len; + if (unlikely(!pkt->frag_iter && pkt->remaining_len)) { + pkt->remaining_len = 0; + pkt->extra_count = 0; + pr_err_ratelimited("malformed sk_buff at %s\n", + queue->name); + break; + } + } while (offset < XEN_PAGE_SIZE && pkt->remaining_len > 0); if (pkt->remaining_len > 0)