From 5745b8232e942abd5e16e85fa9b27cc21324acf0 Mon Sep 17 00:00:00 2001
From: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Date: Sun, 3 Apr 2016 22:09:23 +0800
Subject: [PATCH] ipv4: l2tp: fix a potential issue in l2tp_ip_recv
pskb_may_pull() can change skb->data, so we have to load ptr/optr at the
right place.
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
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 ec22078b0914f..42de4ccd159f6 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);
}
--
2.30.2