x25: Patch to fix bug 15678 - x25 accesses fields beyond end of packet.

Here is a patch to stop X.25 examining fields beyond the end of the packet.

For example, when a simple CALL ACCEPTED was received:

	10 10 0f

x25_parse_facilities was attempting to decode the FACILITIES field, but this
packet contains no facilities field.

Signed-off-by: John Hughes <john@calva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/x25.h b/include/net/x25.h
index 9baa07d..33f67fb 100644
--- a/include/net/x25.h
+++ b/include/net/x25.h
@@ -182,6 +182,10 @@
 extern int  sysctl_x25_ack_holdback_timeout;
 extern int  sysctl_x25_forward;
 
+extern int x25_parse_address_block(struct sk_buff *skb,
+		struct x25_address *called_addr,
+		struct x25_address *calling_addr);
+
 extern int  x25_addr_ntoa(unsigned char *, struct x25_address *,
 			  struct x25_address *);
 extern int  x25_addr_aton(unsigned char *, struct x25_address *,