Changeset 92621 in webkit

Timestamp:

Aug 8, 2011 12:41:12 PM (13 years ago)

Author:

bfulgham@webkit.org

Message:

WebView::performLayeredWindowUpdate() crashes with
NULL pointer when using layered window updates.
​https://bugs.webkit.org/show_bug.cgi?id=60618

Reviewed by Adam Roben.

During resize operations, the backing store will be destroyed if
the window's size (either height or width) is set to zero. The
bug was identified when a user first resized a WebView to zero
dimensions, then attempted to perform a MoveWindow. The paint
message triggered by the MoveWindow attempted to use the layered
window update logic, which encountered the nulled backing store.

• WebView.cpp:

(WebView::performLayeredWindowUpdate): Add an early

return when there is no backing store to blend with.

Location:

trunk/Source/WebKit/win

Files:

• ChangeLog (modified) (1 diff)
• WebView.cpp (modified) (1 diff)

trunk/Source/WebKit/win/ChangeLog

@@ +1 @@
+2011-08-05  Brent Fulgham  <bfulgham@webkit.org>
+
+        WebView::performLayeredWindowUpdate() crashes with
+        NULL pointer when using layered window updates.
+        https://bugs.webkit.org/show_bug.cgi?id=60618
+
+        Reviewed by Adam Roben.
+
+        During resize operations, the backing store will be destroyed if
+        the window's size (either height or width) is set to zero. The
+        bug was identified when a user first resized a WebView to zero
+        dimensions, then attempted to perform a MoveWindow. The paint
+        message triggered by the MoveWindow attempted to use the layered
+        window update logic, which encountered the nulled backing store.
+
+        * WebView.cpp:
+        (WebView::performLayeredWindowUpdate): Add an early
+         return when there is no backing store to blend with.
+
 2011-08-05  Anders Carlsson  <andersca@apple.com>
 

trunk/Source/WebKit/win/WebView.cpp

@@ -1001 +1001 @@
 void WebView::performLayeredWindowUpdate()
 {
+    // The backing store may have been destroyed if the window rect was set to zero height or zero width.
+    if (!m_backingStoreBitmap)
+        return;
+
     HDC hdcScreen = ::GetDC(m_viewWindow);
     OwnPtr<HDC> hdcMem = adoptPtr(::CreateCompatibleDC(hdcScreen));