ipv4: l2tp: fix a potential issue in l2tp_ip_recv

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 <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
This commit is contained in:
Haishuang Yan 2016-04-03 22:09:23 +08:00 committed by Willy Tarreau
parent c75e78a494
commit e8bf435fb7
1 changed files with 5 additions and 3 deletions

View File

@ -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);
}