ReadFile giving "invalid access to memory location"

I'm writing a plugin for another application. I have successfully been able to use WriteFile(), but I am getting errors with ReadFile().

Code:

void loadLayers()
{
	DWORD dwRead = 0;
	hLayerFile = CreateFile("ltmp.dat", 
                                                     GENERIC_READ, 
                                                     FILE_SHARE_READ, 
                                                     NULL, 
                                                     OPEN_EXISTING, 
                                                     FILE_ATTRIBUTE_NORMAL, 
                                                     NULL);
	char *urls = NULL;
	DWORD fileSize = GetFileSize(hLayerFile, NULL);

	if (ReadFile(hLayerFile, urls, fileSize, &dwRead, NULL) == 0)
	{//ReadFile() does return 0 and here I call GetLastError()

GetLastError() returns "invalid access to memory location". I'm confused, and have even tried subtracting and adding 1 to fileSize, but I can't see what the problem is. Any help?

You declare urls but don't allocate any memory for it (see ReadFile). Also, you should check the return value of CreateFile to ensure a successful operation.

Code:

DWORD dwRead;
hLayerFile = CreateFile("ltmp.dat", GENERIC_READ, FILE_SHARE_READ, 
                         NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if (hLayerFile!=INVALID_HANDLE_VALUE)
  {
  DWORD fileSize = GetFileSize(hLayerFile, NULL);
  char *urls = new char[filesize];  //don't forget to delete[] urls when done
  if (ReadFile(hLayerFile, urls, fileSize, &dwRead, NULL) == 0)
  //etc
  }

Yea, I check CreateFile, but I took it out to size down the code to look at. I probably should have mentioned that. Thanks for the help.