Fix #11005: Company value overflows (#11012)

* Clamp park value to prevent integer overflow.

* Replace casting with built-in clamping.

* Add changlog entry for #11005.

* Modify casting to prevent skewed company value.

* Increment network version

Co-authored-by: Michał Janiszewski <janisozaur@gmail.com>

distribution/changelog.txt

@@ -4,6 +4,7 @@
 - Fix: [#475] Water sides drawn incorrectly (original bug).
 - Fix: [#6123, #7907, #9472, #11028] Cannot build some track designs with 4 stations (original bug).
 - Fix: [#7094] Back wall edge texture in water missing.
+- Fix: [#11005] Company value overflows.
 - Fix: [#11027] Third color on walls becomes black when saving.
 
 0.2.5 (2020-03-24)

src/openrct2/network/Network.cpp

@@ -31,7 +31,7 @@
 // This string specifies which version of network stream current build uses.
 // It is used for making sure only compatible builds get connected, even within
 // single OpenRCT2 version.
-#define NETWORK_STREAM_VERSION "1"
+#define NETWORK_STREAM_VERSION "2"
 #define NETWORK_STREAM_ID OPENRCT2_VERSION "-" NETWORK_STREAM_VERSION
 
 static Peep* _pickup_peep = nullptr;

src/openrct2/world/Park.cpp

@@ -33,6 +33,7 @@
 #include "../ride/RideData.h"
 #include "../ride/ShopItem.h"
 #include "../scenario/Scenario.h"
+#include "../util/Util.h"
 #include "../windows/Intent.h"
 #include "Entrance.h"
 #include "Map.h"
@@ -516,7 +517,12 @@ money32 Park::CalculateRideValue(const Ride* ride) const
 
 money32 Park::CalculateCompanyValue() const
 {
-    return finance_get_current_cash() + gParkValue - gBankLoan;
+    money32 result = gParkValue - gBankLoan;
+
+    // Clamp addition to prevent overflow
+    result = add_clamp_money32(result, finance_get_current_cash());
+
+    return result;
 }
 
 money16 Park::CalculateTotalRideValueForMoney() const