Access Violation, UE 4.26.2 STAR WARS Jedi: Survivor

[Omega172]

The exception

//Exception thrown at 0x00007FF87BFCAD0B (Dumper-7.dll) in JediSurvivor.exe: 0xC0000005: Access violation reading location 0x00000000000000B0.
// Line 21 OffsetFinder.h

// Related code
template<int Alignement = 4, typename T>
inline int32_t FindOffset(std::vector<std::pair<void*, T>>& ObjectValuePair, int MinOffset = 0x28, int MaxOffset = 0x1A0)
{
	int32_t HighestFoundOffset = MinOffset;

	for (int i = 0; i < ObjectValuePair.size(); i++)
	{
		uint8_t* BytePtr = (uint8_t*)(ObjectValuePair[i].first);

		for (int j = HighestFoundOffset; j < MaxOffset; j += Alignement)
		{
			if ((*reinterpret_cast<T*>(BytePtr + j)) == ObjectValuePair[i].second && j >= HighestFoundOffset)
			{
				if (j > HighestFoundOffset)
				{
					HighestFoundOffset = j;
					i = 0;
				}
				j = MaxOffset;
			}
		}
	}

	return HighestFoundOffset != MinOffset ? HighestFoundOffset : OffsetNotFound;
}

// Call Stack
/*
>	Dumper-7.dll!OffsetFinder::FindOffset<4,enum EFunctionFlags>(std::vector<std::pair<void *,enum EFunctionFlags>,std::allocator<std::pair<void *,enum EFunctionFlags>>> & ObjectValuePair, int MinOffset, int MaxOffset) Line 21	C++
 	Dumper-7.dll!OffsetFinder::FindFunctionFlagsOffset() Line 413	C++
 	Dumper-7.dll!Off::Init() Line 249	C++
 	Dumper-7.dll!Generator::InitEngineCore() Line 84	C++
 	Dumper-7.dll!MainThread(HINSTANCE__ * Module) Line 54	C++
 	kernel32.dll!00007ffa0ae3257d()	Unknown
 	ntdll.dll!00007ffa0becaa48()	Unknown

*/

Dumper 7 output

Started Generation [Dumper-7]!

Dumper-7 by me, you & him


Searching for GObjects...

Found FChunkedFixedUObjectArray GObjects at offset 0x6902668

Found 'FNamePool GNames' at offset 0x68E9FC0

Found FName::AppendString at Offset 0x1D4D360

Off::UStruct::Children: 0x48
Off::Field::Next: 0x28
Off::UStruct::SuperStruct: 0x40
Off::UStruct::Size: 0x58
Off::UStruct::MinAlignemnts: 0x5C
Off::UClass::CastFlags: 0xD8
Game uses FProperty system

Off::UStruct::ChildProperties: 0x50
Off::FField::Next: 0x18
Off::FField::Name: 0x28
Off::FField::Flags: 0x30
Off::UClass::ClassDefaultObject: 0x120
Off::UEnum::Names: 0x40

[Fischsalat]

Which function in wasn't found in OffsetFinder::FindFunctionFlagsOffset? Aka which is nullptr in the Infos vector.

[Omega172]

[Fischsalat]

In that case I propose for you to comment out OffsetFinder.h Line411 as a temporary fix.

If this fix works please DON'T close this issue, and send me the GObjects-Dump.txt file generated by the dumper.

[Omega172]

New error after attempting the suggested fix

// Exception thrown at 0x00007FF9FF4D6EC9 (Dumper-7.dll) in JediSurvivor.exe: 0xC0000005: Access violation reading location 0x0000000000000008.
// Line 151 ObjectArray.cpp

void ObjectArray::InitializeChunkSize(uint8_t* ChunksPtr)
{
	int IndexOffset = 0x0;
	uint8* ObjAtIdx374 = (uint8*)ByIndex(ChunksPtr, 0x374, SizeOfFUObjectItem, FUObjectItemInitialOffset, 0x10000);
	uint8* ObjAtIdx106 = (uint8*)ByIndex(ChunksPtr, 0x106, SizeOfFUObjectItem, FUObjectItemInitialOffset, 0x10000);

	for (int i = 0x8; i < 0x20; i++)
	{
		if (*reinterpret_cast<int32*>(ObjAtIdx374 + i) == 0x374 && *reinterpret_cast<int32*>(ObjAtIdx106 + i) == 0x106)
		{
			IndexOffset = i;
			break;
		}
	}

	int IndexToCheck = 0x10400;
	while (ObjectArray::Num() > IndexToCheck)
	{
		if (void* Obj = ByIndex(ChunksPtr, IndexToCheck, SizeOfFUObjectItem, FUObjectItemInitialOffset, 0x10000))
		{
			const bool bIsTrue = *reinterpret_cast<int32*>((uint8*)Obj + IndexOffset) != IndexToCheck;
			NumElementsPerChunk = bIsTrue ? 0x10400 : 0x10000;
			break;
		}
		IndexToCheck += 0x10400;
	}

	Off::InSDK::ObjArray::ChunkSize = NumElementsPerChunk;
}

// Call Stack
/*
>	Dumper-7.dll!ObjectArray::InitializeChunkSize(unsigned char * ChunksPtr) Line 151	C++
 	Dumper-7.dll!ObjectArray::Init(bool bScanAllMemory) Line 271	C++
 	Dumper-7.dll!Generator::InitEngineCore() Line 82	C++
 	Dumper-7.dll!MainThread(HINSTANCE__ * Module) Line 54	C++
 	kernel32.dll!00007ffb4e41257d()	Unknown
 	ntdll.dll!00007ffb4ff2aa48()	Unknown
 */

Dumper 7 Output

Started Generation [Dumper-7]!

Dumper-7 by me, you & him


Searching for GObjects...

Found FChunkedFixedUObjectArray GObjects at offset 0x5e74024

[Fischsalat]

So without the fix you reached the Offset initialization, but with the fix you're now crashing at an earlier point?
That doesn't make any sense, are you sure that crash occurs consistently?

[Omega172]

The crash is indeed occurring constantly, and i have made sure too use the same game launch method every time., to launch without EA

[Fischsalat]

Still doesn't make any sense. Why would the dll suddenly crash earlier? Does it work if you revert the fix?

[Omega172]

I have no clue how I got that second error.
To be 100% sure I got proper reproducible results , I reverted any changes I made and rebuilt

With no changes just pulled and compiled, I get the same error as my initial message.

When the fix is applied

// Commented out OffsetFinder.h Line411
//Infos.push_back({ ObjectArray::FindObjectFast("SwitchLevel").GetAddress(), EFunctionFlags::Exec | EFunctionFlags::Native | EFunctionFlags::Public });

/*
Exception thrown at 0x00007FF9C2906961 (Dumper-7.dll) in JediSurvivor.exe: 0xC0000005: Access violation reading location 0x00000000000000D8.
OffsetFinder.h Line 434
*/

inline int32_t FindFunctionNativeFuncOffset()
{
	std::vector<std::pair<void*, EFunctionFlags>> Infos;

	uintptr_t WasInputKeyJustPressed = reinterpret_cast<uintptr_t>(ObjectArray::FindObjectFast("WasInputKeyJustPressed").GetAddress());
	uintptr_t ToggleSpeaking = reinterpret_cast<uintptr_t>(ObjectArray::FindObjectFast("ToggleSpeaking").GetAddress());
	uintptr_t SwitchLevel = reinterpret_cast<uintptr_t>(ObjectArray::FindObjectFast("SwitchLevel").GetAddress());

	for (int i = 0x40; i < 0x140; i += 8)
	{
		if (IsInProcessRange(*reinterpret_cast<uintptr_t*>(WasInputKeyJustPressed + i)) && IsInProcessRange(*reinterpret_cast<uintptr_t*>(ToggleSpeaking + i)) && IsInProcessRange(*reinterpret_cast<uintptr_t*>(SwitchLevel + i)))
			return i;
	}

	return 0x0;
}

/*
>	Dumper-7.dll!OffsetFinder::FindFunctionNativeFuncOffset() Line 434	C++
 	Dumper-7.dll!Off::Init() Line 252	C++
 	Dumper-7.dll!Generator::InitEngineCore() Line 84	C++
 	Dumper-7.dll!MainThread(HINSTANCE__ * Module) Line 54	C++
 	kernel32.dll!00007ffb4e41257d()	Unknown
 	ntdll.dll!00007ffb4ff2aa48()	Unknown
*/

/*
Started Generation [Dumper-7]!

Dumper-7 by me, you & him


Searching for GObjects...

Found FChunkedFixedUObjectArray GObjects at offset 0x6902668

Found 'FNamePool GNames' at offset 0x68E9FC0

Found FName::AppendString at Offset 0x1D4D360

Off::UStruct::Children: 0x48
Off::Field::Next: 0x28
Off::UStruct::SuperStruct: 0x40
Off::UStruct::Size: 0x58
Off::UStruct::MinAlignemnts: 0x5C
Off::UClass::CastFlags: 0xD8
Game uses FProperty system

Off::UStruct::ChildProperties: 0x50
Off::FField::Next: 0x18
Off::FField::Name: 0x28
Off::FField::Flags: 0x30
Off::UClass::ClassDefaultObject: 0x120
Off::UEnum::Names: 0x40
Off::UFunction::FunctionFlags: 0xB0
*/

What i believe is the issue

uintptr_t SwitchLevel = reinterpret_cast<uintptr_t>(ObjectArray::FindObjectFast("SwitchLevel").GetAddress());

// According to the debugger these are the values
// Switchlevel = 0;
// i = 216; Which is 0xD8
// 0 + 0xD8 = 0xD8;
IsInProcessRange(*reinterpret_cast<uintptr_t*>(SwitchLevel + i); // The crash is caused here trying to access location 0xD8

I double & triple checked by making sure to launch the game with the same method everytime and using the same Debug x64 built DLL, and I got the same error every time.

[Omega172]

So it seems to me like the object SwitchLevel just cannot ever be found.

[Fischsalat]

In that case try also commenting out lines/places using SwitchLevel. Would also be nice if you could send me an object dump of your game. You can call ObjectArray::DumpObjects() on a line before the crash.

[Omega172]

Object Dump:
https://mega.nz/file/CIgREJBY#VeqzG4BIuyIyQi5CP_J1jiR4fAGhz8NwM9e8g5E_I7g had to upload it because GitHub only allows files that are 25mb but it was 35mb

[xVoidie]

I had the same issue what worked for me in manually defining the offsets for UFunction