[PATCH v2 0/1] MR10324: Draft: win32u: Fix deadlock when setting hdc_src to the window's self DC.

[Zhao Yi (＠Zhaoyi)]

Supersed !9180 and !9177

When hdc_src is the window's self DC, Within the NtUserUpdateLayeredWindow function, there exists the following call sequence: window_surface_lock()-\>NtGdiAlphaBlend()-\>window_surface_unlock(). However, the implementation of the NtGdiAlphaBlend() function calls the windrv_GetImage() function, which internally invokes lock_surface() and unlock_surface(). In this situation, window_surface_lock() is called first to acquire a lock. When lock_surface() is subsequently called to acquire the same lock, the initial lock has not yet been released, ultimately resulting in a deadlock.

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  v2: win32u: Fix deadlock when setting hdc_src to the window's self DC.
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10324

[PATCH v2 1/1] win32u: Fix deadlock when setting hdc_src to the window's self DC.

[Zhao Yi]

From: Zhao Yi <[e-mail]>

Signed-off-by: Zhao Yi <[e-mail]>
---
 dlls/win32u/window.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/dlls/win32u/window.c b/dlls/win32u/window.c
index fc129df0785..21bbb289c79 100644
--- a/dlls/win32u/window.c
+++ b/dlls/win32u/window.c
@@ -2688,27 +2688,49 @@ BOOL WINAPI NtUserUpdateLayeredWindow( HWND hwnd, HDC hdc_dst, const POINT *pts_
         BLENDFUNCTION src_blend = { AC_SRC_OVER, 0, 255, 0 };
         RECT rect = new_rects.window, src_rect;
         HDC hdc = NULL;
+        HDC hdc_src_tmp = hdc_src;
+        BOOL use_tmp_dc = FALSE;
+        HDC hdc_tmp = NULL;
+        HBITMAP hbm_tmp = NULL;
 
         OffsetRect( &rect, -rect.left, -rect.top );
         intersect_rect( &rect, &rect, &surface_rect );
+        if (dirty) intersect_rect( &rect, &rect, dirty );
+        src_rect = rect;
+        if (pts_src) OffsetRect( &src_rect, pts_src->x, pts_src->y );
+
+        if (NtUserWindowFromDC( hdc_src ) == hwnd)
+        {
+            if (!(hdc_tmp = NtGdiCreateCompatibleDC( 0 ))) goto done;
+            if (!(hbm_tmp = NtGdiCreateCompatibleBitmap( hdc_src, rect.right - rect.left, rect.bottom - rect.top )))
+            {
+                NtGdiDeleteObjectApp( hdc_tmp );
+                goto done;
+            }
+            NtGdiSelectBitmap( hdc_tmp, hbm_tmp );
+            NtGdiBitBlt( hdc_tmp, 0, 0, rect.right - rect.left, rect.bottom - rect.top, hdc_src, src_rect.left, src_rect.top, SRCCOPY, 0, 0 );
+            hdc_src_tmp = hdc_tmp;
+            use_tmp_dc = TRUE;
+        }
 
         if (!(hdc = NtGdiCreateCompatibleDC( 0 ))) goto done;
         window_surface_lock( surface );
         NtGdiSelectBitmap( hdc, surface->color_bitmap );
 
-        if (dirty) intersect_rect( &rect, &rect, dirty );
         NtGdiPatBlt( hdc, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, BLACKNESS );
-
-        src_rect = rect;
-        if (pts_src) OffsetRect( &src_rect, pts_src->x, pts_src->y );
         NtGdiTransformPoints( hdc_src, (POINT *)&src_rect, (POINT *)&src_rect, 2, NtGdiDPtoLP );
 
         ret = NtGdiAlphaBlend( hdc, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top,
-                               hdc_src, src_rect.left, src_rect.top, src_rect.right - src_rect.left, src_rect.bottom - src_rect.top,
+                               hdc_src_tmp, src_rect.left, src_rect.top, src_rect.right - src_rect.left, src_rect.bottom - src_rect.top,
                                *(DWORD *)&src_blend, 0 );
         if (ret) add_bounds_rect( &surface->bounds, &rect );
 
         NtGdiDeleteObjectApp( hdc );
+        if (use_tmp_dc)
+        {
+            NtGdiDeleteObjectApp( hbm_tmp );
+            NtGdiDeleteObjectApp( hdc_tmp );
+        }
         window_surface_unlock( surface );
 
         if (!(flags & ULW_COLORKEY)) key = CLR_INVALID;
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10324

[PATCH v2 0/1] MR10324: win32u: Fix deadlock when setting hdc_src to the window's self DC.

[Zhao Yi (＠Zhaoyi)]

- v2: When **hdc_src** is the **window's self DC**, Create a **compatible DC**, copy the contents of **hdc_src** to this **compatible DC**, and then use this **compatible DC** as the source for **AlphaBlend**.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10324#note_132508