Uniform way to guard ACS stack and variables

ACS VM stack and map/world/global variables arrays are now checked for out of bounds access

src/p_acs.cpp

@@ -835,12 +835,12 @@ inline int uallong(const int &foo)
 //============================================================================
 
 // ACS variables with world scope
-int32_t ACS_WorldVars[NUM_WORLDVARS];
+static BoundsCheckingArray<int32_t, NUM_WORLDVARS> ACS_WorldVars;
-FWorldGlobalArray ACS_WorldArrays[NUM_WORLDVARS];
+static BoundsCheckingArray<FWorldGlobalArray, NUM_WORLDVARS> ACS_WorldArrays;
 
 // ACS variables with global scope
-int32_t ACS_GlobalVars[NUM_GLOBALVARS];
+BoundsCheckingArray<int32_t, NUM_GLOBALVARS> ACS_GlobalVars;
-FWorldGlobalArray ACS_GlobalArrays[NUM_GLOBALVARS];
+BoundsCheckingArray<FWorldGlobalArray, NUM_GLOBALVARS> ACS_GlobalArrays;
 
 //----------------------------------------------------------------------------
 //
@@ -851,21 +851,7 @@ FWorldGlobalArray ACS_GlobalArrays[NUM_GLOBALVARS];
 //
 //----------------------------------------------------------------------------
 
-struct FACSStackMemory
+using FACSStackMemory = BoundsCheckingArray<int32_t, STACK_SIZE>;
-{
-	int32_t& operator[](const size_t index)
-	{
-		if (index >= STACK_SIZE)
-		{
-			I_Error("Corrupted stack pointer in ACS VM");
-		}
-
-		return buffer[index];
-	}
-
-private:
-	int32_t buffer[STACK_SIZE];
-};
 
 struct FACSStack
 {
@@ -1470,10 +1456,10 @@ void ACSStringPool::UnlockForLevel(int lnum)
 
 void P_MarkWorldVarStrings()
 {
-	GlobalACSStrings.MarkStringArray(ACS_WorldVars, countof(ACS_WorldVars));
+	GlobalACSStrings.MarkStringArray(ACS_WorldVars.Pointer(), ACS_WorldVars.Size());
-	for (size_t i = 0; i < countof(ACS_WorldArrays); ++i)
+	for (size_t i = 0; i < ACS_WorldArrays.Size(); ++i)
 	{
-		GlobalACSStrings.MarkStringMap(ACS_WorldArrays[i]);
+		GlobalACSStrings.MarkStringMap(ACS_WorldArrays.Pointer()[i]);
 	}
 }
 
@@ -1485,10 +1471,10 @@ void P_MarkWorldVarStrings()
 
 void P_MarkGlobalVarStrings()
 {
-	GlobalACSStrings.MarkStringArray(ACS_GlobalVars, countof(ACS_GlobalVars));
+	GlobalACSStrings.MarkStringArray(ACS_GlobalVars.Pointer(), ACS_GlobalVars.Size());
-	for (size_t i = 0; i < countof(ACS_GlobalArrays); ++i)
+	for (size_t i = 0; i < ACS_GlobalArrays.Size(); ++i)
 	{
-		GlobalACSStrings.MarkStringMap(ACS_GlobalArrays[i]);
+		GlobalACSStrings.MarkStringMap(ACS_GlobalArrays.Pointer()[i]);
 	}
 }
 
@@ -1571,14 +1557,14 @@ void P_ClearACSVars(bool alsoglobal)
 {
 	int i;
 
-	memset (ACS_WorldVars, 0, sizeof(ACS_WorldVars));
+	ACS_WorldVars.Fill(0);
 	for (i = 0; i < NUM_WORLDVARS; ++i)
 	{
 		ACS_WorldArrays[i].Clear ();
 	}
 	if (alsoglobal)
 	{
-		memset (ACS_GlobalVars, 0, sizeof(ACS_GlobalVars));
+		ACS_GlobalVars.Fill(0);
 		for (i = 0; i < NUM_GLOBALVARS; ++i)
 		{
 			ACS_GlobalArrays[i].Clear ();
@@ -1726,10 +1712,10 @@ static void ReadArrayVars (FSerializer &file, FWorldGlobalArray *vars, size_t co
 
 void P_ReadACSVars(FSerializer &arc)
 {
-	ReadVars (arc, ACS_WorldVars, NUM_WORLDVARS, "acsworldvars");
+	ReadVars (arc, ACS_WorldVars.Pointer(), NUM_WORLDVARS, "acsworldvars");
-	ReadVars (arc, ACS_GlobalVars, NUM_GLOBALVARS, "acsglobalvars");
+	ReadVars (arc, ACS_GlobalVars.Pointer(), NUM_GLOBALVARS, "acsglobalvars");
-	ReadArrayVars (arc, ACS_WorldArrays, NUM_WORLDVARS, "acsworldarrays");
+	ReadArrayVars (arc, ACS_WorldArrays.Pointer(), NUM_WORLDVARS, "acsworldarrays");
-	ReadArrayVars (arc, ACS_GlobalArrays, NUM_GLOBALVARS, "acsglobalarrays");
+	ReadArrayVars (arc, ACS_GlobalArrays.Pointer(), NUM_GLOBALVARS, "acsglobalarrays");
 	GlobalACSStrings.ReadStrings(arc, "acsglobalstrings");
 }
 
@@ -1741,10 +1727,10 @@ void P_ReadACSVars(FSerializer &arc)
 
 void P_WriteACSVars(FSerializer &arc)
 {
-	WriteVars (arc, ACS_WorldVars, NUM_WORLDVARS, "acsworldvars");
+	WriteVars (arc, ACS_WorldVars.Pointer(), NUM_WORLDVARS, "acsworldvars");
-	WriteVars (arc, ACS_GlobalVars, NUM_GLOBALVARS, "acsglobalvars");
+	WriteVars (arc, ACS_GlobalVars.Pointer(), NUM_GLOBALVARS, "acsglobalvars");
-	WriteArrayVars (arc, ACS_WorldArrays, NUM_WORLDVARS, "acsworldarrays");
+	WriteArrayVars (arc, ACS_WorldArrays.Pointer(), NUM_WORLDVARS, "acsworldarrays");
-	WriteArrayVars (arc, ACS_GlobalArrays, NUM_GLOBALVARS, "acsglobalarrays");
+	WriteArrayVars (arc, ACS_GlobalArrays.Pointer(), NUM_GLOBALVARS, "acsglobalarrays");
 	GlobalACSStrings.WriteStrings(arc, "acsglobalstrings");
 }
 

src/p_acs.h

@@ -60,13 +60,32 @@ struct InitIntToZero
 };
 typedef TMap<int32_t, int32_t, THashTraits<int32_t>, InitIntToZero> FWorldGlobalArray;
 
-// ACS variables with world scope
+// Type of elements count is unsigned int instead of size_t to match ACSStringPool interface
-extern int32_t ACS_WorldVars[NUM_WORLDVARS];
+template <typename T, unsigned int N>
-extern FWorldGlobalArray ACS_WorldArrays[NUM_WORLDVARS];
+struct BoundsCheckingArray
+{
+	T &operator[](const unsigned int index)
+	{
+		if (index >= N)
+		{
+			I_Error("Out of bounds memory access in ACS VM");
+		}
+
+		return buffer[index];
+	}
+
+	T *Pointer() { return buffer; }
+	unsigned int Size() const { return N; }
+
+	void Fill(const T &value) { std::fill(std::begin(buffer), std::end(buffer), value); }
+
+private:
+	T buffer[N];
+};
 
 // ACS variables with global scope
-extern int32_t ACS_GlobalVars[NUM_GLOBALVARS];
+extern BoundsCheckingArray<int32_t, NUM_GLOBALVARS> ACS_GlobalVars;
-extern FWorldGlobalArray ACS_GlobalArrays[NUM_GLOBALVARS];
+extern BoundsCheckingArray<FWorldGlobalArray, NUM_GLOBALVARS> ACS_GlobalArrays;
 
 #define LIBRARYID_MASK			0xFFF00000
 #define LIBRARYID_SHIFT			20
@@ -359,7 +378,7 @@ public:
 	ACSProfileInfo *GetFunctionProfileData(ScriptFunction *func) { return GetFunctionProfileData((int)(func - (ScriptFunction *)Functions)); }
 	const char *LookupString (uint32_t index) const;
 
-	int32_t *MapVars[NUM_MAPVARS];
+	BoundsCheckingArray<int32_t *, NUM_MAPVARS> MapVars;
 
 	static FBehavior *StaticLoadModule (int lumpnum, FileReader * fr=NULL, int len=0);
 	static void StaticLoadDefaultModules ();