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=-10.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY,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 53014C282C3 for ; Thu, 24 Jan 2019 07:49:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22939218A3 for ; Thu, 24 Jan 2019 07:49:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="4RGDP72x" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726384AbfAXHtr (ORCPT ); Thu, 24 Jan 2019 02:49:47 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:38438 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725931AbfAXHtq (ORCPT ); Thu, 24 Jan 2019 02:49:46 -0500 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.22/8.16.0.22) with SMTP id x0O7ngSg073504; Thu, 24 Jan 2019 07:49:42 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id; s=corp-2018-07-02; bh=79k543V7ECjqzn7pXaWHjqKc8NtLwS3OwsxfPDisQyw=; b=4RGDP72xIraH/ceknGG+LI7kp0/VTYjff2c1DTjww+1k3E9BR/y4ur1nyLJdKq2bGTTW aL2HgBezcapWoWXSu6+Cjn4oTbZ+dPa+CmgsdbGZmPqGjgaW45iSU46VsXzo5IoeR6fb 5kVe9brX8zLfUzq9aDo2drhiI/hhcUzw1QyXJeJRgvE2MK5SpgeLHj7HaN+qWuJbSmX2 PoNKN5ob+EVdEM+K+TuIBcFUjm09IPiLxfdoq5dk5AjuHZMKo2pt1tz3rxrAMArcaI8J EXFbpygZDbM3bF4g9ifMHt/bkZRvDDzP/2MJu4bsJElYpp/5ipuonqCtGMX7FkSyzNnW Hg== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2130.oracle.com with ESMTP id 2q3sdepf3u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 24 Jan 2019 07:49:42 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x0O7ngpV016687 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 24 Jan 2019 07:49:42 GMT Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x0O7nffx017538; Thu, 24 Jan 2019 07:49:41 GMT Received: from jw-M900.cn.oracle.com (/10.182.69.163) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 23 Jan 2019 23:49:41 -0800 From: Jacob Wen To: netdev@vger.kernel.org Cc: eric.dumazet@gmail.com, g.nault@alphalink.fr Subject: [PATCH net-next v2] net: l2tp: fix reading optional fields of L2TPv3 Date: Thu, 24 Jan 2019 15:49:17 +0800 Message-Id: <20190124074917.31173-1-jian.w.wen@oracle.com> X-Mailer: git-send-email 2.17.1 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9145 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=955 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1901240057 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Use pskb_may_pull() to make sure the optional fields are in skb linear parts, so we can safely read them later. It's easy to reproduce the issue with a net driver that supports paged skb data. Just create a L2TPv3 over IP tunnel and then generates some network traffic. Once reproduced, rx err in /sys/kernel/debug/l2tp/tunnels will increase. Signed-off-by: Jacob Wen --- Changes in v2: 1. Only fix L2TPv3 to make code simple. To fix both L2TPv3 and L2TPv2, we'd better refactor l2tp_recv_common. It's complicated to do so. 2. Reloading pointers after pskb_may_pull --- net/l2tp/l2tp_core.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 26f1d435696a..e9a17c634c1a 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -625,6 +625,20 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, int offset; u32 ns, nr; + if (tunnel->version != L2TP_HDR_VER_2) { + int opt_len = session->peer_cookie_len + + l2tp_get_l2specific_len(session); + + if (opt_len > 0) { + int off = ptr - optr; + + if (!pskb_may_pull(skb, off + opt_len)) + goto discard; + optr = skb->data; + ptr = optr + off; + } + } + /* Parse and check optional cookie */ if (session->peer_cookie_len > 0) { if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { -- 2.17.1