Add overflow checking for CHECKVAL.

LuaEngine.cpp

@@ -462,6 +462,47 @@ void Eluna::Push(lua_State* L, Object const* obj)
     }
 }
 
+static int32 CheckIntegerRange(lua_State *L, int narg, int32 max, int32 min)
+{
+    int32 value = luaL_checklong(L, narg);
+    char error_buffer[64];
+
+    if (value > max)
+    {
+        snprintf(error_buffer, 64, "value must be less than %u", max);
+        return luaL_argerror(L, narg, error_buffer);
+    }
+
+    if (value < min)
+    {
+        snprintf(error_buffer, 64, "value must be greater than %d", min);
+        return luaL_argerror(L, narg, error_buffer);
+    }
+
+    return value;
+}
+
+// This function does not work properly for anything larger than uint16.
+static uint32 CheckUnsignedRange(lua_State *L, int narg, uint32 max)
+{
+    int32 value = luaL_checklong(L, narg);
+    char error_buffer[64];
+
+    if (value < 0)
+        return luaL_argerror(L, narg, "value must be greater than 0");
+
+    // Prevent signed-unsigned mismatch.
+    // This cast is safe because the value is not negative.
+    uint32 u_value = value;
+    if (u_value > max)
+    {
+        snprintf(error_buffer, 64, "value must be less than %u", max);
+        return luaL_argerror(L, narg, error_buffer);
+    }
+
+    return u_value;
+}
+
 template<> bool Eluna::CHECKVAL<bool>(lua_State* L, int narg)
 {
     return lua_toboolean(L, narg);
@@ -476,19 +517,19 @@ template<> double Eluna::CHECKVAL<double>(lua_State* L, int narg)
 }
 template<> int8 Eluna::CHECKVAL<int8>(lua_State* L, int narg)
 {
-    return luaL_checkint(L, narg);
+    return CheckIntegerRange(L, narg, SCHAR_MAX, SCHAR_MIN);
 }
 template<> uint8 Eluna::CHECKVAL<uint8>(lua_State* L, int narg)
 {
-    return luaL_checkunsigned(L, narg);
+    return CheckUnsignedRange(L, narg, UCHAR_MAX);
 }
 template<> int16 Eluna::CHECKVAL<int16>(lua_State* L, int narg)
 {
-    return luaL_checkint(L, narg);
+    return CheckIntegerRange(L, narg, SHRT_MIN, SHRT_MAX);
 }
 template<> uint16 Eluna::CHECKVAL<uint16>(lua_State* L, int narg)
 {
-    return luaL_checkunsigned(L, narg);
+    return CheckUnsignedRange(L, narg, USHRT_MAX);
 }
 template<> int32 Eluna::CHECKVAL<int32>(lua_State* L, int narg)
 {
@@ -496,7 +537,9 @@ template<> int32 Eluna::CHECKVAL<int32>(lua_State* L, int narg)
 }
 template<> uint32 Eluna::CHECKVAL<uint32>(lua_State* L, int narg)
 {
-    return luaL_checkunsigned(L, narg);
+    // If a negative value is passed instead, it will become a large positive value.
+    // There is no way to catch this.
+    return luaL_checklong(L, narg);
 }
 template<> const char* Eluna::CHECKVAL<const char*>(lua_State* L, int narg)
 {