Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753605AbcDZUZk (ORCPT ); Tue, 26 Apr 2016 16:25:40 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:58252 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753466AbcDZUZf (ORCPT ); Tue, 26 Apr 2016 16:25:35 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Haishuang Yan , "David S . Miller" , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 18/66] ipv4: l2tp: fix a potential issue in l2tp_ip_recv Date: Tue, 26 Apr 2016 13:24:09 -0700 Message-Id: <1461702297-7792-19-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1461702297-7792-1-git-send-email-kamal@canonical.com> References: <1461702297-7792-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1396 Lines: 49 3.19.8-ckt20 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Haishuang Yan [ Upstream commit 5745b8232e942abd5e16e85fa9b27cc21324acf0 ] 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: Kamal Mostafa --- 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 05dfc8a..cb24e2b 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); } -- 2.7.4