From 9bc3028eb73bc473721746ce24ed11db796435dc Mon Sep 17 00:00:00 2001
From: Seth Hillbrand <seth@kipro-pcb.com>
Date: Fri, 7 Aug 2020 13:37:00 -0700
Subject: [PATCH] pcbnew: Prevent use of non-connected item in ratsnest

We need to be careful in the connectivity system to always use
dyn_cast/dynamic_cast and check the return when dealing with board
items.  Getting non-connected items will result in null nets when
propagated.

Fixes https://gitlab.com/kicad/code/kicad/issues/5082

(cherry picked from commit 406de569644c86036e3c0d80bf15c173e890a3d0)
---
 pcbnew/connectivity/connectivity_algo.cpp | 25 ++++++++++++++---------
 pcbnew/connectivity/connectivity_data.cpp |  3 ++-
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/pcbnew/connectivity/connectivity_algo.cpp b/pcbnew/connectivity/connectivity_algo.cpp
index 9e7135f825..354acce95e 100644
--- a/pcbnew/connectivity/connectivity_algo.cpp
+++ b/pcbnew/connectivity/connectivity_algo.cpp
@@ -39,6 +39,11 @@
 
 bool CN_CONNECTIVITY_ALGO::Remove( BOARD_ITEM* aItem )
 {
+    BOARD_CONNECTED_ITEM* citem = dyn_cast<BOARD_CONNECTED_ITEM*>( aItem );
+
+    if( !citem )
+        return false;
+
     markItemNetAsDirty( aItem );
 
     switch( aItem->Type() )
@@ -46,35 +51,35 @@ bool CN_CONNECTIVITY_ALGO::Remove( BOARD_ITEM* aItem )
     case PCB_MODULE_T:
         for( auto pad : static_cast<MODULE*>( aItem ) -> Pads() )
         {
-            m_itemMap[ static_cast<BOARD_CONNECTED_ITEM*>( pad ) ].MarkItemsAsInvalid();
-            m_itemMap.erase( static_cast<BOARD_CONNECTED_ITEM*>( pad ) );
+            m_itemMap[pad].MarkItemsAsInvalid();
+            m_itemMap.erase( pad );
         }
 
         m_itemList.SetDirty( true );
         break;
 
     case PCB_PAD_T:
-        m_itemMap[ static_cast<BOARD_CONNECTED_ITEM*>( aItem ) ].MarkItemsAsInvalid();
-        m_itemMap.erase( static_cast<BOARD_CONNECTED_ITEM*>( aItem ) );
+        m_itemMap[citem].MarkItemsAsInvalid();
+        m_itemMap.erase( citem );
         m_itemList.SetDirty( true );
         break;
 
     case PCB_TRACE_T:
-        m_itemMap[ static_cast<BOARD_CONNECTED_ITEM*>( aItem ) ].MarkItemsAsInvalid();
-        m_itemMap.erase( static_cast<BOARD_CONNECTED_ITEM*>( aItem ) );
+        m_itemMap[citem].MarkItemsAsInvalid();
+        m_itemMap.erase( citem );
         m_itemList.SetDirty( true );
         break;
 
     case PCB_VIA_T:
-        m_itemMap[ static_cast<BOARD_CONNECTED_ITEM*>( aItem ) ].MarkItemsAsInvalid();
-        m_itemMap.erase( static_cast<BOARD_CONNECTED_ITEM*>( aItem ) );
+        m_itemMap[citem].MarkItemsAsInvalid();
+        m_itemMap.erase( citem );
         m_itemList.SetDirty( true );
         break;
 
     case PCB_ZONE_AREA_T:
     {
-        m_itemMap[ static_cast<BOARD_CONNECTED_ITEM*>( aItem ) ].MarkItemsAsInvalid();
-        m_itemMap.erase ( static_cast<BOARD_CONNECTED_ITEM*>( aItem ) );
+        m_itemMap[citem].MarkItemsAsInvalid();
+        m_itemMap.erase ( citem );
         m_itemList.SetDirty( true );
         break;
     }
diff --git a/pcbnew/connectivity/connectivity_data.cpp b/pcbnew/connectivity/connectivity_data.cpp
index a262093eee..0f3d8af123 100644
--- a/pcbnew/connectivity/connectivity_data.cpp
+++ b/pcbnew/connectivity/connectivity_data.cpp
@@ -206,7 +206,8 @@ void CONNECTIVITY_DATA::BlockRatsnestItems( const std::vector<BOARD_ITEM*>& aIte
         }
         else
         {
-            citems.push_back( static_cast<BOARD_CONNECTED_ITEM*>(item) );
+            if( auto citem = dynamic_cast<BOARD_CONNECTED_ITEM*>( item ) )
+                citems.push_back( citem );
         }
     }