[Mono-bugs] [Bug 378191] New: Rapidly calling DoDragDrop can cause NullReferenceException

bugzilla_noreply at novell.com bugzilla_noreply at novell.com
Tue Apr 8 19:40:17 EDT 2008


           Summary: Rapidly calling DoDragDrop can cause
           Product: Mono: Class Libraries
           Version: 1.9.0
          Platform: x86-64
        OS/Version: RHEL 5
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: Windows.Forms
        AssignedTo: mono-bugs at lists.ximian.com
        ReportedBy: flemingt at lunainnovations.com
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---

If the user of an application causes it to rapidly call DoDragDrop, then the
application may terminate with a NullReferenceException.

To reproduce:
  1. Build and run the attached test case.
  2. Rapidly click a mouse button (triple-click often triggers the problem for

Example output (RHEL 5 x86-64, Mono 1.9 built from source):

Unhandled Exception: System.NullReferenceException: Object reference not set to
an instance of an object
  at System.Windows.Forms.DataObject.SetData (System.Object data) [0x00000] 
  at System.Windows.Forms.X11Dnd.SetDataWithFormats (System.Object value)
  at System.Windows.Forms.X11Dnd.ConvertData (System.Windows.Forms.XEvent&
xevent) [0x00000] 
  at System.Windows.Forms.X11Dnd.Accepting_HandleEnterEvent
(System.Windows.Forms.XEvent& xevent) [0x00000] 
  at System.Windows.Forms.X11Dnd.HandleClientMessage
(System.Windows.Forms.XEvent& xevent) [0x00000] 
  at System.Windows.Forms.XplatUIX11.GetMessage (System.Object queue_id,
System.Windows.Forms.MSG& msg, IntPtr handle, Int32 wFilterMin, Int32
wFilterMax) [0x00000] 
  at System.Windows.Forms.XplatUI.GetMessage (System.Object queue_id,
System.Windows.Forms.MSG& msg, IntPtr hWnd, Int32 wFilterMin, Int32 wFilterMax)
  at System.Windows.Forms.Application.RunLoop (Boolean Modal,
System.Windows.Forms.ApplicationContext context) [0x00000] 
  at System.Windows.Forms.Application.Run
(System.Windows.Forms.ApplicationContext context) [0x00000] 
  at System.Windows.Forms.Application.Run (System.Windows.Forms.Form mainForm)
  at DragDropTest.Main () [0x00000]

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