From 2e852f758b3fbc18ad30ec75d8c62b5d5238e70a Mon Sep 17 00:00:00 2001
From: Joakim Eriksson <joakime@sics.se>
Date: Thu, 26 Nov 2015 14:19:12 +0100
Subject: [PATCH] added a null check on the lladdr before the memcmp.

---
 core/net/ipv6/uip-nd6.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/core/net/ipv6/uip-nd6.c b/core/net/ipv6/uip-nd6.c
index 316172fb2..62b3a64cb 100644
--- a/core/net/ipv6/uip-nd6.c
+++ b/core/net/ipv6/uip-nd6.c
@@ -490,14 +490,16 @@ na_input(void)
     PRINTF("NA received is bad\n");
     goto discard;
   } else {
+    const uip_lladdr_t *lladdr;
     nbr = uip_ds6_nbr_lookup(&UIP_ND6_NA_BUF->tgtipaddr);
     if(nbr == NULL) {
       goto discard;
     }
 
+    lladdr = uip_ds6_nbr_get_ll(nbr);
     if(nd6_opt_llao != NULL) {
-      is_llchange =
-        memcmp(&nd6_opt_llao[UIP_ND6_OPT_DATA_OFFSET], uip_ds6_nbr_get_ll(nbr),
+      is_llchange = lladdr == NULL ||
+        memcmp(&nd6_opt_llao[UIP_ND6_OPT_DATA_OFFSET], lladdr,
                UIP_LLADDR_LEN);
     }
     if(nbr->state == NBR_INCOMPLETE) {