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=-8.2 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 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 E4A13C282C3 for ; Thu, 24 Jan 2019 07:54:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AEE372184C for ; Thu, 24 Jan 2019 07:54:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="29LlgpUk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727222AbfAXHyv (ORCPT ); Thu, 24 Jan 2019 02:54:51 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:44234 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725931AbfAXHyv (ORCPT ); Thu, 24 Jan 2019 02:54:51 -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 x0O7nKDs073142; Thu, 24 Jan 2019 07:51:21 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=r2xzOk0YMDFmFPEQ87gp+aRdpQiW9oWeisP2K0wlDco=; b=29LlgpUkjm0qejCkWJ/xW777RCjb2eczEZ7QnikSMOkCga7DuqF1pBN2z8JZQ6gyxhP1 EdYxXAMMtncYfedyKS6ZfwSI6VPTkOZTPk0IYM5fWwVX+0Hn51OV4OcWb63AGmg/rpPZ J+Gstl+hKwX/fIZXsGlLPrHXuypgxB8bJTbtnn9xfxkm+0cKezzPr4L8sPyQFEZQqNJH 3Np0o3GmPxX6G1I7l0y/KZNo/JwDmQE+zQDsplSIE5ARAEijzaXjtyeZio2AG8Hekvyp 6PYAHjyh+CV7ZZBHO/ISJNukYpaO+n7oNB5MUnUvglGPwwmaNVaS6Fe4dMyO8A2iIZDs Sg== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2130.oracle.com with ESMTP id 2q3sdepf9g-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 24 Jan 2019 07:51:21 +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 x0O7pKmm021684 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 24 Jan 2019 07:51:20 GMT Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x0O7pKaP031570; Thu, 24 Jan 2019 07:51:20 GMT Received: from [10.182.69.163] (/10.182.69.163) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 23 Jan 2019 23:51:20 -0800 Subject: Re: [PATCH net-next v1] l2tp: fix reading optional fields To: Eric Dumazet , netdev@vger.kernel.org Cc: jchapman@katalix.com References: <20190123023050.29062-1-jian.w.wen@oracle.com> From: Jacob Wen Message-ID: <731d94aa-b8a6-1ae4-853d-0a9a24dc698f@oracle.com> Date: Thu, 24 Jan 2019 15:51:17 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9145 signatures=668682 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=8.0.1-1810050000 definitions=main-1901240057 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 1/23/19 10:51 AM, Eric Dumazet wrote: > > On 01/22/2019 06:30 PM, Jacob Wen wrote: >> Use pskb_may_pull() to make sure the optional fields are in skb linear >> parts. >> >> Signed-off-by: Jacob Wen >> --- >> v1: fix warning: ISO C90 forbids mixed declarations and code >> --- >> net/l2tp/l2tp_core.c | 12 +++++++++++- >> 1 file changed, 11 insertions(+), 1 deletion(-) >> >> diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c >> index 26f1d435696a..c0dfa2bcd218 100644 >> --- a/net/l2tp/l2tp_core.c >> +++ b/net/l2tp/l2tp_core.c >> @@ -627,6 +627,8 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, >> >> /* Parse and check optional cookie */ >> if (session->peer_cookie_len > 0) { >> + if (!pskb_may_pull(skb, ptr - optr + session->peer_cookie_len)) >> + goto discard; > This is completely buggy. > > After pskb_may_pull(), the ptr and optr pointers might point to freed data. > > So the memcmp() might crash hard. Fixed in v2. Thanks. > >> if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { >> l2tp_info(tunnel, L2TP_MSG_DATA, >> "%s: cookie mismatch (%u/%u). Discarding.\n", >> @@ -649,6 +651,8 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, >> L2TP_SKB_CB(skb)->has_seq = 0; >> if (tunnel->version == L2TP_HDR_VER_2) { >> if (hdrflags & L2TP_HDRFLAG_S) { >> + if (!pskb_may_pull(skb, ptr - optr + 4)) >> + goto discard; >> ns = ntohs(*(__be16 *) ptr); >> ptr += 2; >> nr = ntohs(*(__be16 *) ptr); >> @@ -663,8 +667,12 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, >> session->name, ns, nr, session->nr); >> } >> } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { >> - u32 l2h = ntohl(*(__be32 *) ptr); >> + u32 l2h; >> + >> + if (!pskb_may_pull(skb, ptr - optr + 4)) >> + goto discard; >> >> + l2h = ntohl(*(__be32 *) ptr); >> if (l2h & 0x40000000) { >> ns = l2h & 0x00ffffff; >> >> @@ -729,6 +737,8 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, >> if (tunnel->version == L2TP_HDR_VER_2) { >> /* If offset bit set, skip it. */ >> if (hdrflags & L2TP_HDRFLAG_O) { >> + if (!pskb_may_pull(skb, ptr - optr + 2)) >> + goto discard; >> offset = ntohs(*(__be16 *)ptr); >> ptr += 2 + offset; >> } >> -- Jacob