char* func() {
   char *rez;
   rez = (char *)malloc(1024);
   //..
   return rez;
}

void main() {
   char *pc;
   pc = func();
   //...
   free(pc);
}

void CTestDllAllocExeDlg::OnOK() 
{

	char* m = myalloc();
	free( m );
	MessageBox( "OK" );

	CDialog::OnOK();
}

char* myalloc()
{
	return (char*)malloc( 10 );
}

**int _CrtIsValidHeapPointer() - verify pointer is from 'local' heap
*
*Purpose:
*       Verify pointer is not only a valid pointer but also that it is from
*       the 'local' heap. Pointers from another copy of the C runtime (even in the
*       same process) will be caught.
*
*Entry:
*       const void * pUserData     - pointer of interest
*
*Return:
*       TRUE - if valid and from local heap
*       FALSE otherwise
******************************************************************************