EXCEPTION_ACCESS_VIOLATION writing address 0x0000000080401bc0

Development Programming & Scripting C++
, , ,
1 
void UHighlightManager::ClearTileColors()
{
	if (Instance == nullptr)
	{
		UE_LOG(LogHighlight, Error, TEXT("Instance is null"));
		return;
	}
	//if (Instance->TextureData == nullptr) //this isn't allowed, apparently
	//{
	//	UE_LOG(LogHighlight, Error, TEXT("Instance->TextureData is null"));
	//	return;
	//}

	for (int x = 0; x < (int)(Instance->TileSize); x++)
	{
		for (int y = 0; y < (int)(Instance->TileSize); y++)
		{
			if (Instance->TileData[x + y * (Instance->TileSize)].A == 0) continue;

			Instance->TileData[x + y * (Instance->TileSize)] = FColor(0, 0, 0, 0);
			if (!Instance->TextureData.IsValidIndex(x * 32 + (y * 32) * Instance->TextureSize)
				|| !Instance->TextureData.IsValidIndex(x * 32 + 31 + (y * 32 + 31) * Instance->TextureSize))
			{
				UE_LOG(LogHighlight, Error, TEXT("Invalid index: %d <> %d (%d, %d)"), x * 32 + (y * 32) * Instance->TextureSize, x * 32 + 31 + (y * 32 + 31) * Instance->TextureSize, x, y);
			}
			else
			{
				for (int i = 0; i < 32; i++)
				{
					for (int j = 0; j < 32; j++)
					{
						Instance->TextureData[x * 32 + i + (y * 32 + j) * Instance->TextureSize] = FColor(0, 0, 0, 0); //Crashing here
					}
				}
			}

			Instance->bHasTextureUpdate = true;
		}
	}
}

not sure what it’s failing to access; Instance, Instance->TextureData, and Instance->TextureSize are all successfully accessed before that line. Unless FColor(0, 0, 0, 0) is somehow responsible

2

Can you print out which iteration through the loop it’s failing on? Is it the first, last, deterministic, non-deterministic etc.?

3

x=0, y=0 on the two most recent repro’s. Haven’t checked i and j, as that would result in a considerable amount of spam, and the error doesn’t happen every time ClearTileColors() is called

4

No chance Instance is getting deleted by something else while you’re in the middle of the loop?

Might have to suffer the spam to figure this one out.

5

sure enough, something is destroying the HighlightManager Instance