Title: [239847] trunk/Source/WebCore
- Revision
- 239847
- Author
- simon.fra...@apple.com
- Date
- 2019-01-10 14:50:13 -0800 (Thu, 10 Jan 2019)
Log Message
Fix rare crash under ScrollbarThemeMac::paintScrollCorner()
https://bugs.webkit.org/show_bug.cgi?id=193337
rdar://problem/47179993
Reviewed by Zalan Bujtas.
Async image decoding can trigger a FrameView::traverseForPaintInvalidation() fake paint,
which creates a GraphicsContext with no platform context. However, we could hit ScrollView::paintScrollbars()
which tried to get at the platform context, and then crashed.
So protect two functions in ScrollbarThemeMac with if (context.paintingDisabled()) checks. I verified
that other scrollbar-related painting code paths were already protected.
Hard to test because it depends on async image decoding timing.
* platform/mac/ScrollbarThemeMac.mm:
(WebCore::ScrollbarThemeMac::paint):
(WebCore::ScrollbarThemeMac::paintScrollCorner):
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (239846 => 239847)
--- trunk/Source/WebCore/ChangeLog 2019-01-10 22:36:56 UTC (rev 239846)
+++ trunk/Source/WebCore/ChangeLog 2019-01-10 22:50:13 UTC (rev 239847)
@@ -1,3 +1,24 @@
+2019-01-10 Simon Fraser <simon.fra...@apple.com>
+
+ Fix rare crash under ScrollbarThemeMac::paintScrollCorner()
+ https://bugs.webkit.org/show_bug.cgi?id=193337
+ rdar://problem/47179993
+
+ Reviewed by Zalan Bujtas.
+
+ Async image decoding can trigger a FrameView::traverseForPaintInvalidation() fake paint,
+ which creates a GraphicsContext with no platform context. However, we could hit ScrollView::paintScrollbars()
+ which tried to get at the platform context, and then crashed.
+
+ So protect two functions in ScrollbarThemeMac with if (context.paintingDisabled()) checks. I verified
+ that other scrollbar-related painting code paths were already protected.
+
+ Hard to test because it depends on async image decoding timing.
+
+ * platform/mac/ScrollbarThemeMac.mm:
+ (WebCore::ScrollbarThemeMac::paint):
+ (WebCore::ScrollbarThemeMac::paintScrollCorner):
+
2019-01-10 Myles C. Maxfield <mmaxfi...@apple.com>
[WHLSL] Implement parser AST nodes
Modified: trunk/Source/WebCore/platform/mac/ScrollbarThemeMac.mm (239846 => 239847)
--- trunk/Source/WebCore/platform/mac/ScrollbarThemeMac.mm 2019-01-10 22:36:56 UTC (rev 239846)
+++ trunk/Source/WebCore/platform/mac/ScrollbarThemeMac.mm 2019-01-10 22:50:13 UTC (rev 239847)
@@ -550,6 +550,9 @@
bool ScrollbarThemeMac::paint(Scrollbar& scrollbar, GraphicsContext& context, const IntRect& damageRect)
{
+ if (context.paintingDisabled())
+ return false;
+
setPaintCharacteristicsForScrollbar(scrollbar);
if (scrollbar.supportsUpdateOnSecondaryThread())
@@ -568,6 +571,9 @@
void ScrollbarThemeMac::paintScrollCorner(GraphicsContext& context, const IntRect& cornerRect)
{
+ if (context.paintingDisabled())
+ return;
+
LocalCurrentGraphicsContext localContext(context);
auto cornerDrawingOptions = @{ (__bridge NSString *)kCUIWidgetKey: (__bridge NSString *)kCUIWidgetScrollBarTrackCorner,
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