Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753852AbcDCOJe (ORCPT ); Sun, 3 Apr 2016 10:09:34 -0400 Received: from cmccmta3.chinamobile.com ([221.176.66.81]:8345 "EHLO cmccmta3.chinamobile.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751582AbcDCOJd (ORCPT ); Sun, 3 Apr 2016 10:09:33 -0400 X-RM-TRANSID: 2eec570124158cd-8dcea X-RM-SPAM-FLAG: 00000000 X-RM-TRANSID: 2ee5570124168ce-55abb From: Haishuang Yan To: "David S. Miller" Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Haishuang Yan Subject: [PATCH 2/2] ipv6: l2tp: fix a potential issue in l2tp_ip6_recv Date: Sun, 3 Apr 2016 22:09:24 +0800 Message-Id: <1459692564-3998-2-git-send-email-yanhaishuang@cmss.chinamobile.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1459692564-3998-1-git-send-email-yanhaishuang@cmss.chinamobile.com> References: <1459692564-3998-1-git-send-email-yanhaishuang@cmss.chinamobile.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1030 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_ip6.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c index 6b54ff3..cd47990 100644 --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -136,12 +136,11 @@ static int l2tp_ip6_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; @@ -169,6 +168,9 @@ static int l2tp_ip6_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