1 files changed, 24 insertions, 20 deletions

diff --git a/drivers/net/pppol2tp.c b/drivers/net/pppol2tp.c
index ed8ead4..440e190 100644
--- a/drivers/net/pppol2tp.c
+++ b/drivers/net/pppol2tp.c
@@ -491,44 +491,46 @@ static int pppol2tp_recv_core(struct sock *sock, struct sk_buff *skb)
 	u16 hdrflags;
 	u16 tunnel_id, session_id;
 	int length;
-	struct udphdr *uh;
+	int offset;
 
 	tunnel = pppol2tp_sock_to_tunnel(sock);
 	if (tunnel == NULL)
 		goto error;
 
+	/* UDP always verifies the packet length. */
+	__skb_pull(skb, sizeof(struct udphdr));
+
 	/* Short packet? */
-	if (skb->len < sizeof(struct udphdr)) {
+	if (!pskb_may_pull(skb, 12)) {
 		PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_INFO,
 		       "%s: recv short packet (len=%d)\n", tunnel->name, skb->len);
 		goto error;
 	}
 
 	/* Point to L2TP header */
-	ptr = skb->data + sizeof(struct udphdr);
+	ptr = skb->data;
 
 	/* Get L2TP header flags */
 	hdrflags = ntohs(*(__be16*)ptr);
 
 	/* Trace packet contents, if enabled */
 	if (tunnel->debug & PPPOL2TP_MSG_DATA) {
+		length = min(16u, skb->len);
+		if (!pskb_may_pull(skb, length))
+			goto error;
+
 		printk(KERN_DEBUG "%s: recv: ", tunnel->name);
 
-		for (length = 0; length < 16; length++)
-			printk(" %02X", ptr[length]);
+		offset = 0;
+		do {
+			printk(" %02X", ptr[offset]);
+		} while (++offset < length);
+
 		printk("\n");
 	}
 
 	/* Get length of L2TP packet */
-	uh = (struct udphdr *) skb_transport_header(skb);
-	length = ntohs(uh->len) - sizeof(struct udphdr);
-
-	/* Too short? */
-	if (length < 12) {
-		PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_INFO,
-		       "%s: recv short L2TP packet (len=%d)\n", tunnel->name, length);
-		goto error;
-	}
+	length = skb->len;
 
 	/* If type is control packet, it is handled by userspace. */
 	if (hdrflags & L2TP_HDRFLAG_T) {
@@ -606,7 +608,6 @@ static int pppol2tp_recv_core(struct sock *sock, struct sk_buff *skb)
 			       "%s: recv data has no seq numbers when required. "
 			       "Discarding\n", session->name);
 			session->stats.rx_seq_discards++;
-			session->stats.rx_errors++;
 			goto discard;
 		}
 
@@ -625,7 +626,6 @@ static int pppol2tp_recv_core(struct sock *sock, struct sk_buff *skb)
 			       "%s: recv data has no seq numbers when required. "
 			       "Discarding\n", session->name);
 			session->stats.rx_seq_discards++;
-			session->stats.rx_errors++;
 			goto discard;
 		}
 
@@ -634,10 +634,14 @@ static int pppol2tp_recv_core(struct sock *sock, struct sk_buff *skb)
 	}
 
 	/* If offset bit set, skip it. */
-	if (hdrflags & L2TP_HDRFLAG_O)
-		ptr += 2 + ntohs(*(__be16 *) ptr);
+	if (hdrflags & L2TP_HDRFLAG_O) {
+		offset = ntohs(*(__be16 *)ptr);
+		skb->transport_header += 2 + offset;
+		if (!pskb_may_pull(skb, skb_transport_offset(skb) + 2))
+			goto discard;
+	}
 
-	skb_pull(skb, ptr - skb->data);
+	__skb_pull(skb, skb_transport_offset(skb));
 
 	/* Skip PPP header, if present.	 In testing, Microsoft L2TP clients
 	 * don't send the PPP header (PPP header compression enabled), but
@@ -673,7 +677,6 @@ static int pppol2tp_recv_core(struct sock *sock, struct sk_buff *skb)
 			 */
 			if (PPPOL2TP_SKB_CB(skb)->ns != session->nr) {
 				session->stats.rx_seq_discards++;
-				session->stats.rx_errors++;
 				PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
 				       "%s: oos pkt %hu len %d discarded, "
 				       "waiting for %hu, reorder_q_len=%d\n",
@@ -698,6 +701,7 @@ static int pppol2tp_recv_core(struct sock *sock, struct sk_buff *skb)
 	return 0;
 
 discard:
+	session->stats.rx_errors++;
 	kfree_skb(skb);
 	sock_put(session->sock);