ip: check if interface has link-local address

Type: fix

Change-Id: I9d3344374738f8cf883cffb4715c76b50bb4bfce
Signed-off-by: Stanislav Zaikin <zstaseg@gmail.com>
diff --git a/src/vnet/fib/fib_sas.c b/src/vnet/fib/fib_sas.c
index b607a0b..230fcd1 100644
--- a/src/vnet/fib/fib_sas.c
+++ b/src/vnet/fib/fib_sas.c
@@ -102,7 +102,12 @@
      */
     if (ip6_address_is_link_local_unicast (dst))
     {
-        ip6_address_copy (src, ip6_get_link_local_address (sw_if_index));
+        const ip6_address_t *ll = ip6_get_link_local_address (sw_if_index);
+        if (NULL == ll)
+        {
+            return (false);
+        }
+        ip6_address_copy (src, ll);
         return (true);
     }