Bug 256403

Summary: Defer AX object cache update as an event loop task instead of a post layout task
Product: WebKit Reporter: Ryosuke Niwa <rniwa>
Component: AccessibilityAssignee: Ryosuke Niwa <rniwa>
Status: RESOLVED FIXED    
Severity: Normal CC: andresg_22, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Local Build   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 256354, 256383    

Description Ryosuke Niwa 2023-05-05 17:56:13 PDT 
We currently update AX caches as a post layout task.
This is problematic because it can lead to arbitrary script execution:
e.g.

3   0x2836d4250 WebCore::EventDispatcher::dispatchEvent(WebCore::Node&, WebCore::Event&)
4   0x28376d6ac WebCore::Node::dispatchEvent(WebCore::Event&)
5   0x283699750 WebCore::Element::dispatchFocusEvent(WTF::RefPtr<WebCore::Element, WTF::RawPtrTraits<WebCore::Element>, WTF::DefaultRefDerefTraits<WebCore::Element>>&&, WebCore::FocusOptions const&)
6   0x2835c477c WebCore::Document::setFocusedElement(WebCore::Element*, WebCore::FocusOptions const&)
7   0x2843b3b48 WebCore::FocusController::setFocusedElement(WebCore::Element*, WebCore::LocalFrame&, WebCore::FocusOptions const&)
8   0x283698d64 WebCore::Element::focus(WebCore::FocusOptions const&)
9   0x282b8b80c WebCore::AccessibilityNodeObject::setFocused(bool)
10  0x282af3d4c WebCore::AXObjectCache::focusCurrentModal()
11  0x282afeda4 WebCore::AXObjectCache::performDeferredCacheUpdate()
12  0x28441f0c4 WebCore::LocalFrameView::performPostLayoutTasks()
13  0x28442a760 WebCore::LocalFrameViewLayoutContext::runAsynchronousTasks()
14  0x28442b7e8 WebCore::LocalFrameViewLayoutContext::runOrScheduleAsynchronousTasks()
15  0x28442b110 WebCore::LocalFrameViewLayoutContext::performLayout()
16  0x28440969c WebCore::LocalFrameViewLayoutContext::layout()
17  0x28441cbb0 WebCore::LocalFrameView::updateContentsSize()
18  0x2846a2f90 WebCore::ScrollView::updateScrollbars(WebCore::IntPoint const&)
19  0x2846a4858 WebCore::ScrollView::setContentsSize(WebCore::IntSize const&)
20  0x28440cafc WebCore::LocalFrameView::setContentsSize(WebCore::IntSize const&)
21  0x284406f7c WebCore::LocalFrameView::adjustViewSize()
22  0x28442afc0 WebCore::LocalFrameViewLayoutContext::performLayout()
23  0x28440969c WebCore::LocalFrameViewLayoutContext::layout()
24  0x2835adde8 WebCore::Document::updateLayout()
Comment 1 Radar WebKit Bug Importer 2023-05-05 17:56:28 PDT 
<rdar://problem/108974696>
Comment 2 Ryosuke Niwa 2023-05-05 18:06:20 PDT 
Pull request: https://github.com/WebKit/WebKit/pull/13528
Comment 3 EWS 2023-05-08 15:46:11 PDT 
Committed 263832@main (e8027f0de539): <https://commits.webkit.org/263832@main>

Reviewed commits have been landed. Closing PR #13528 and removing active labels.