Fix errors found from coverity scan (#2386)

Fix errors found by coverity

-CID: 652656, 652657, 670381, 670382: Dereference null return
-CID: 652655 Improper use of negative value

Author: Arto Kinnunen

source/6LoWPAN/ws/ws_bbr_api.c

@@ -242,7 +242,10 @@ static if_address_entry_t *ws_bbr_slaac_generate(protocol_interface_info_entry_t
 
 static void ws_bbr_slaac_remove(protocol_interface_info_entry_t *cur, uint8_t *ula_prefix)
 {
-    icmpv6_slaac_prefix_update(cur, ula_prefix, 64, 0, 0);
+    if (cur) {
+        icmpv6_slaac_prefix_update(cur, ula_prefix, 64, 0, 0);
+    }
+
     addr_policy_table_delete_entry(ula_prefix, 64);
 }
 
@@ -371,14 +374,16 @@ static void ws_bbr_dhcp_server_start(protocol_interface_info_entry_t *cur, uint8
 }
 static void ws_bbr_dhcp_server_stop(protocol_interface_info_entry_t *cur, uint8_t *global_id)
 {
+    if (!cur) {
+        return;
+    }
     uint8_t temp_address[16];
     memcpy(temp_address, global_id, 8);
     memset(temp_address + 8, 0, 8);
     tr_debug("DHCP server deactivate %s", trace_ipv6(temp_address));
     DHCPv6_server_service_delete(cur->id, global_id, false);
     //Delete Client
     dhcp_client_global_address_delete(cur->id, NULL, temp_address);
-
 }
 
 static void ws_bbr_routing_stop(protocol_interface_info_entry_t *cur)
@@ -725,7 +730,6 @@ void ws_bbr_stop(int8_t interface_id)
     protocol_interface_info_entry_t *cur = protocol_stack_interface_info_get_by_id(interface_id);
 
     ws_bbr_routing_stop(cur);
-
     backbone_interface_id = -1;
     current_instance_id++;
 

source/6LoWPAN/ws/ws_management_api.c

@@ -41,9 +41,11 @@ int ws_management_node_init(
     protocol_interface_info_entry_t *cur;
 
     cur = protocol_stack_interface_info_get_by_id(interface_id);
+
     if (interface_id >= 0 && (!cur || !ws_info(cur))) {
         return -1;
     }
+
     if (!network_name_ptr || !fhss_timer_ptr) {
         return -2;
     }
@@ -70,7 +72,9 @@ int ws_management_node_init(
         return -4;
     }
 
-    cur->ws_info->fhss_timer_ptr = fhss_timer_ptr;
+    if (cur && ws_info(cur)) {
+        cur->ws_info->fhss_timer_ptr = fhss_timer_ptr;
+    }
 
     return 0;
 }
@@ -398,7 +402,7 @@ int ws_management_channel_plan_set(
     protocol_interface_info_entry_t *cur;
 
     cur = protocol_stack_interface_info_get_by_id(interface_id);
-    if (interface_id >= 0 && (!cur || !ws_info(cur))) {
+    if (!cur || !ws_info(cur)) {
         return -1;
     }
     cur->ws_info->hopping_schdule.channel_plan = channel_plan;

source/Security/protocols/sec_prot_keys.c

@@ -923,7 +923,7 @@ uint8_t sec_prot_keys_gtk_count(sec_prot_gtk_keys_t *gtks)
 void sec_prot_keys_ptk_installed_gtk_hash_clear_all(sec_prot_keys_t *sec_keys)
 {
     for (uint8_t index = 0; index < GTK_NUM; index++) {
-        memset(sec_keys->ins_gtk_hash[sec_keys->gtk_set_index].hash, 0, INS_GTK_HASH_LEN);
+        memset(sec_keys->ins_gtk_hash[index].hash, 0, INS_GTK_HASH_LEN);
     }
     sec_keys->ins_gtk_hash_set = 0;
     sec_keys->ins_gtk_4wh_hash_set = 0;