From d0a79ff0850ca3008716bf96b9f9689fd6248194 Mon Sep 17 00:00:00 2001
From: sg <goldsimon@gmx.de>
Date: Tue, 19 Jul 2016 22:01:42 +0200
Subject: [PATCH] fixed bug #48477 (ARP input packet might update static entry)

---
 CHANGELOG              | 3 +++
 src/core/ipv4/etharp.c | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG
index 65b33d2d..263d19e7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -321,6 +321,9 @@ HISTORY
 
   ++ Bugfixes:
 
+  2016-07-19: Simon Goldschmidt
+  * etharp.c: fixed bug #48477 (ARP input packet might update static entry)
+
   2016-07-11: Simon Goldschmidt
   * tcp_in.c: fixed bug #48476 (TCP sent callback called wrongly due to picking
     up old pcb->acked
diff --git a/src/core/ipv4/etharp.c b/src/core/ipv4/etharp.c
index 28d33cc8..5481d3bd 100644
--- a/src/core/ipv4/etharp.c
+++ b/src/core/ipv4/etharp.c
@@ -480,6 +480,9 @@ etharp_update_arp_entry(struct netif *netif, const ip4_addr_t *ipaddr, struct et
   if (flags & ETHARP_FLAG_STATIC_ENTRY) {
     /* record static type */
     arp_table[i].state = ETHARP_STATE_STATIC;
+  } else if (arp_table[i].state == ETHARP_STATE_STATIC) {
+    /* found entry is a static type, don't overwrite it */
+    return ERR_VAL;
   } else
 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
   {