Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753952AbcDCOJl (ORCPT ); Sun, 3 Apr 2016 10:09:41 -0400 Received: from cmccmta1.chinamobile.com ([221.176.66.79]:5363 "EHLO cmccmta1.chinamobile.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751393AbcDCOJj (ORCPT ); Sun, 3 Apr 2016 10:09:39 -0400 X-RM-TRANSID: 2ee257012416daf-8e19b X-RM-SPAM-FLAG: 00000000 X-RM-TRANSID: 2ee757012413e35-54d43 From: Haishuang Yan To: "David S. Miller" Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Haishuang Yan Subject: [PATCH 1/2] ipv4: l2tp: fix a potential issue in l2tp_ip_recv Date: Sun, 3 Apr 2016 22:09:23 +0800 Message-Id: <1459692564-3998-1-git-send-email-yanhaishuang@cmss.chinamobile.com> X-Mailer: git-send-email 2.5.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1023 Lines: 41 pskb_may_pull() can change skb->data, so we have to load ptr/optr at the right place. Signed-off-by: Haishuang Yan --- 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 ec22078..42de4cc 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); } -- 1.8.3.1