From 05ded5516d262e4d61666fce15a7f51425af838d Mon Sep 17 00:00:00 2001
From: Dirk Ziegelmeier <dirk@ziegelmeier.net>
Date: Tue, 9 Jan 2018 07:51:09 +0100
Subject: [PATCH] Apply patch #9536: netif: Prevent possible NULL pointer
 dereference in netif_set_addr in a modified version

Replace NULL pointers by IP4_ADDR_ANY4 - at sometime in the future, we make the NULL pointer handling obsolete and we can remove all the NULL pointer checks in the code
---
 src/core/netif.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/core/netif.c b/src/core/netif.c
index 375ee433..8330ad7b 100644
--- a/src/core/netif.c
+++ b/src/core/netif.c
@@ -479,6 +479,11 @@ netif_do_set_ipaddr(struct netif *netif, const ip4_addr_t *ipaddr, u8_t callback
 void
 netif_set_ipaddr(struct netif *netif, const ip4_addr_t *ipaddr)
 {
+  /* Don't propagate NULL pointer (IPv4 ANY) to subsequent functions */
+  if (ipaddr == NULL) {
+    ipaddr = IP4_ADDR_ANY4;
+  }
+
   LWIP_ASSERT_CORE_LOCKED();
 
   netif_do_set_ipaddr(netif, ipaddr, 1);
@@ -530,6 +535,11 @@ netif_set_netmask(struct netif *netif, const ip4_addr_t *netmask)
 {
   LWIP_ASSERT_CORE_LOCKED();
 
+  /* Don't propagate NULL pointer (IPv4 ANY) to subsequent functions */
+  if (netmask == NULL) {
+    netmask = IP4_ADDR_ANY4;
+  }
+
   netif_do_set_netmask(netif, netmask, 1);
 }
 
@@ -575,6 +585,11 @@ netif_set_gw(struct netif *netif, const ip4_addr_t *gw)
 {
   LWIP_ASSERT_CORE_LOCKED();
 
+  /* Don't propagate NULL pointer (IPv4 ANY) to subsequent functions */
+  if (gw == NULL) {
+    gw = IP4_ADDR_ANY4;
+  }
+
   netif_do_set_gw(netif, gw, 1);
 }
 
@@ -594,7 +609,22 @@ netif_set_addr(struct netif *netif, const ip4_addr_t *ipaddr, const ip4_addr_t *
 {
 #if LWIP_NETIF_EXT_STATUS_CALLBACK
   u8_t something_changed = 0;
+#endif
 
+  LWIP_ASSERT_CORE_LOCKED();
+
+  /* Don't propagate NULL pointer (IPv4 ANY) to subsequent functions */
+  if (ipaddr == NULL) {
+    ipaddr = IP4_ADDR_ANY4;
+  }
+  if (netmask == NULL) {
+    netmask = IP4_ADDR_ANY4;
+  }
+  if (gw == NULL) {
+    gw = IP4_ADDR_ANY4;
+  }
+
+#if LWIP_NETIF_EXT_STATUS_CALLBACK
   if ((ip4_addr_cmp(ipaddr,  netif_ip4_addr(netif))    == 0) ||
       (ip4_addr_cmp(gw,      netif_ip4_gw(netif))      == 0) ||
       (ip4_addr_cmp(netmask, netif_ip4_netmask(netif)) == 0))   {
@@ -602,8 +632,6 @@ netif_set_addr(struct netif *netif, const ip4_addr_t *ipaddr, const ip4_addr_t *
   }
 #endif
 
-  LWIP_ASSERT_CORE_LOCKED();
-
   if (ip4_addr_isany(ipaddr)) {
     /* when removing an address, we have to remove it *before* changing netmask/gw
        to ensure that tcp RST segment can be sent correctly */