[PATCH 0/1] MR11107: user32:Unify drop_target cleanup at end of drag_drop_drop to avoid spurious...

[zhou zhang (＠zhouzhang)]

user32:Unify drop_target cleanup at end of drag_drop_drop to avoid spurious DragLeave in next DnD session

Change-Id: I1213239a7c7981c4d3f7cb56281e3687527c7885

Bug: drag_drop_drop calls IDropTarget_Drop but fails to Release+NULL drop_target. When the next XdndEnter arrives, drag_drop_enter releases the old data_object, whose destructor sees the stale drop_target is non-NULL,incorrectly calls IDropTarget_DragLeave, and interrupts the new drag session.

Fix: Remove Release+NULL from the else-if branch, add a single Release+NULL after if (drop_file) as the sole cleanup point, avoiding double-release.

Cannot reproduce in Wine tests: DoDragDrop API bypasses clipboard.c entirely and has no stale pointer issue; the X11 DnD path requires cross-process COM deferred Release timing, which cannot be simulated in a simple Wine test case.

MSDN:https://learn.microsoft.com/en-us/windows/win32/api/oleidl/nf-oleidl-idropta...

[drop_receiver.exe](/uploads/85f0571bc354238576bf9e50a62f12e2/drop_receiver.exe)

[drop_receiver.c](/uploads/b409b8a12a352dae9dbd4dab5fa322d2/drop_receiver.c)

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/11107

[PATCH 1/1] user32:Unify drop_target cleanup at end of drag_drop_drop to avoid spurious DragLeave in next DnD session

[zhangzhou]

From: zhangzhou <[e-mail]>

Change-Id: I1213239a7c7981c4d3f7cb56281e3687527c7885
---
 dlls/user32/clipboard.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/dlls/user32/clipboard.c b/dlls/user32/clipboard.c
index 3c3ba7c584c..074e81c13b0 100644
--- a/dlls/user32/clipboard.c
+++ b/dlls/user32/clipboard.c
@@ -1276,8 +1276,6 @@ DWORD drag_drop_drop( HWND hwnd )
     {
         HRESULT hr = IDropTarget_DragLeave( object->drop_target );
         if (FAILED(hr)) WARN( "IDropTarget_DragLeave returned %#lx\n", hr );
-        IDropTarget_Release( object->drop_target );
-        object->drop_target = NULL;
     }
 
     if (drop_file)
@@ -1306,6 +1304,12 @@ DWORD drag_drop_drop( HWND hwnd )
         }
     }
 
+     if (object->drop_target)
+    {
+        IDropTarget_Release( object->drop_target );
+        object->drop_target = NULL;
+    }
+
     TRACE("effectRequested(0x%lx) accept(%d) performed(0x%lx) at x(%ld),y(%ld)\n",
           object->target_effect, accept, effect, object->target_pos.x, object->target_pos.y);
 
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/11107