l2tp: fix l2tp_udp_recv_core()

pskb_may_pull() can change skb->data, so we have to load ptr/optr at the
right place.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index bf8d50c..cf0f308 100644 (file)
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -756,9 +756,6 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
                goto error;
        }
 
-       /* Point to L2TP header */
-       optr = ptr = skb->data;
-
        /* Trace packet contents, if enabled */
        if (tunnel->debug & L2TP_MSG_DATA) {
                length = min(32u, skb->len);
@@ -769,12 +766,15 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 
                offset = 0;
                do {
-                       printk(" %02X", ptr[offset]);
+                       printk(" %02X", skb->data[offset]);
                } while (++offset < length);
 
                printk("\n");
        }
 
+       /* Point to L2TP header */
+       optr = ptr = skb->data;
+
        /* Get L2TP header flags */
        hdrflags = ntohs(*(__be16 *) ptr);