From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752647AbcFEKvK (ORCPT ); Sun, 5 Jun 2016 06:51:10 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:21762 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751348AbcFEKVz (ORCPT ); Sun, 5 Jun 2016 06:21:55 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Haishuang Yan , "David S . Miller" , Willy Tarreau Subject: [PATCH 3.10 072/143] ipv4: l2tp: fix a potential issue in l2tp_ip_recv Date: Sun, 5 Jun 2016 12:19:35 +0200 Message-Id: <1465122046-9645-73-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1465122046-9645-1-git-send-email-w@1wt.eu> References: <1465122046-9645-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Haishuang Yan commit 5745b8232e942abd5e16e85fa9b27cc21324acf0 upstream. pskb_may_pull() can change skb->data, so we have to load ptr/optr at the right place. Signed-off-by: Haishuang Yan Signed-off-by: David S. Miller Signed-off-by: Willy Tarreau --- net/l2tp/l2tp_ip.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index da1a1ce..07f8b97 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -123,12 +123,11 @@ static int l2tp_ip_recv(struct sk_buff *skb) struct l2tp_tunnel *tunnel = NULL; int length; - /* Point to L2TP header */ - optr = ptr = skb->data; - if (!pskb_may_pull(skb, 4)) goto discard; + /* Point to L2TP header */ + optr = ptr = skb->data; session_id = ntohl(*((__be32 *) ptr)); ptr += 4; @@ -156,6 +155,9 @@ static int l2tp_ip_recv(struct sk_buff *skb) if (!pskb_may_pull(skb, length)) goto discard; + /* Point to L2TP header */ + optr = ptr = skb->data; + ptr += 4; pr_debug("%s: ip recv\n", tunnel->name); print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length); } -- 2.8.0.rc2.1.gbe9624a