Bug 164702 – WebContent crash due to checked unsigned overflow in WebCore: WebCore::RenderLayerCompositor::requiresCompositingLayer const + 1104

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[David Kilzer (:ddkilzer)]

Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000001, 0x0000000188bb4798
Termination Signal: Trace/BPT trap: 5
Termination Reason: Namespace SIGNAL, Code 0x5
Terminating Process: exc handler [0]
Triggered by Thread:  0

Filtered syslog:
None found

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   WebCore                       	0x0000000188bb4798 WTF::CrashOnOverflow::crash() + 0 (CheckedArithmetic.h:85)
1   WebCore                       	0x0000000188bb4798 WTF::CrashOnOverflow::overflowed() + 12 (CheckedArithmetic.h:78)
2   WebCore                       	0x0000000188c531f4 WTF::Checked<unsigned int, WTF::CrashOnOverflow>::Checked(WTF::ResultOverflowedTag) + 16 (CheckedArithmetic.h:462)
3   WebCore                       	0x0000000188c531e4 WTF::Checked<unsigned int, WTF::CrashOnOverflow>::Checked(WTF::ResultOverflowedTag) + 12 (CheckedArithmetic.h:461)
4   WebCore                       	0x00000001896143a4 WebCore::RenderLayerCompositor::requiresCompositingLayer(WebCore::RenderLayer const&, WebCore::RenderLayer::ViewportConstrainedNotCompositedReason*) const + 1104 (CheckedArithmetic.h:745)
5   WebCore                       	0x0000000189612d3c WebCore::RenderLayerCompositor::updateBacking(WebCore::RenderLayer&, WebCore::RenderLayerCompositor::CompositingChangeRepaint, WebCore::RenderLayerCompositor::BackingRequired) + 188 (RenderLayerCompositor.cpp:2161)
6   WebCore                       	0x0000000189612c04 WebCore::RenderLayerCompositor::updateLayerCompositingState(WebCore::RenderLayer&, WebCore::RenderLayerCompositor::CompositingChangeRepaint) + 24 (RenderLayerCompositor.cpp:1100)
7   WebCore                       	0x0000000188b71d70 WebCore::RenderLayer::contentChanged(WebCore::ContentChangeType) + 84 (RenderLayer.cpp:424)
8   WebCore                       	0x0000000188b95968 WebCore::HTMLCanvasElement::reset() + 904 (HTMLCanvasElement.cpp:368)
9   WebCore                       	0x0000000188b955c4 WebCore::HTMLCanvasElement::parseAttribute(WebCore::QualifiedName const&, WTF::AtomicString const&) + 76 (HTMLCanvasElement.cpp:130)
10  WebCore                       	0x0000000188e6d7a8 WebCore::Element::attributeChanged(WebCore::QualifiedName const&, WTF::AtomicString const&, WTF::AtomicString const&, WebCore::Element::AttributeModificationReason) + 888 (Element.cpp:1276)
11  WebCore                       	0x0000000188a163f4 WebCore::Element::setAttributeInternal(unsigned int, WebCore::QualifiedName const&, WTF::AtomicString const&, WebCore::Element::SynchronizationOfLazyAttribute) + 820 (Element.cpp:3229)
12  WebCore                       	0x0000000188f88afc WebCore::HTMLCanvasElement::setHeight(unsigned int) + 60 (HTMLCanvasElement.cpp:164)
13  WebCore                       	0x00000001892387f4 WebCore::setJSHTMLCanvasElementHeight(JSC::ExecState*, long long, long long) + 340 (JSHTMLCanvasElement.cpp:206)
14  ???                           	0x00000001088ec0e4 0 + 4438540516
15  ???                           	0x0000000108967ff4 0 + 4439048180
16  JavaScriptCore                	0x00000001885af3b8 vmEntryToJavaScript + 264
17  JavaScriptCore                	0x0000000188481b04 JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*) + 168 (JITCode.cpp:80)
18  JavaScriptCore                	0x0000000187ed2984 JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) + 352 (Interpreter.cpp:1018)
19  JavaScriptCore                	0x0000000188145b9c JSC::profiledCall(JSC::ExecState*, JSC::ProfilingReason, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&) + 164 (CallData.cpp:40)
20  WebCore                       	0x0000000188b51350 WebCore::JSEventListener::handleEvent(WebCore::ScriptExecutionContext*, WebCore::Event*) + 992 (JSMainThreadExecState.h:75)
21  WebCore                       	0x0000000188e8629c WebCore::EventTarget::fireEventListeners(WebCore::Event&, WebCore::EventTargetData*, WTF::Vector<WebCore::RegisteredEventListener, 1ul, WTF::CrashOnOverflow, 16ul>&) + 620 (EventTarget.cpp:291)
22  WebCore                       	0x0000000188e85f4c WebCore::EventTarget::fireEventListeners(WebCore::Event&) + 328 (EventTarget.cpp:235)
23  WebCore                       	0x0000000188e3c930 WebCore::DOMWindow::dispatchEvent(WebCore::Event&, WebCore::EventTarget*) + 280 (DOMWindow.cpp:1920)
24  WebCore                       	0x0000000188b28e5c WebCore::DocumentEventQueue::pendingEventTimerFired() + 216 (DocumentEventQueue.cpp:150)
25  WebCore                       	0x0000000188a14d2c WebCore::ThreadTimers::sharedTimerFiredInternal() + 148 (ThreadTimers.cpp:121)
26  WebCore                       	0x0000000188a14c84 WebCore::timerFired(__CFRunLoopTimer*, void*) + 28 (MainThreadSharedTimerCF.cpp:74)
27  CoreFoundation                	0x0000000183e911d8 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 28 (CFRunLoop.c:1810)
28  CoreFoundation                	0x0000000183e90eec __CFRunLoopDoTimer + 872 (CFRunLoop.c:2349)
29  CoreFoundation                	0x0000000183e907a8 __CFRunLoopDoTimers + 244 (CFRunLoop.c:2488)
30  CoreFoundation                	0x0000000183e8e3a4 __CFRunLoopRun + 1572 (CFRunLoop.c:2973)
31  CoreFoundation                	0x0000000183dbc2b8 CFRunLoopRunSpecific + 444 (CFRunLoop.c:3113)
32  Foundation                    	0x00000001848f926c -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 304 (NSRunLoop.m:367)
33  Foundation                    	0x000000018494daa0 -[NSRunLoop(NSRunLoop) run] + 88 (NSRunLoop.m:389)
34  libxpc.dylib                  	0x0000000182fbfc4c _xpc_objc_main + 660 (main.m:186)
35  libxpc.dylib                  	0x0000000182fc1944 xpc_main + 200 (init.c:1447)
36  com.apple.WebKit.WebContent   	0x00000001000d35bc main + 376 (XPCServiceMain.mm:130)
37  libdyld.dylib                 	0x0000000182d9d5b8 start + 4

[David Kilzer (:ddkilzer)]

<rdar://problem/29236368>

[David Kilzer (:ddkilzer)]

Created attachment 294668 [details]
Patch v1

[David Kilzer (:ddkilzer)]

Comment on attachment 294668 [details]
Patch v1

View in context: https://bugs.webkit.org/attachment.cgi?id=294668&action=review

> LayoutTests/fast/canvas/large-composited-canvas-area.html:24
> +setTimeout(function() {
> +    document.getElementById("canvas").width = "65537";
> +    document.getElementById("canvas").height = "65537";
> +    testPassed("No crash");
> +    finishJSTest();
> +}, 0);

This test doesn't reproduce the crash.  I can't figure out how to reproduce the crashing stack in a layout test.

Simon or Zalan:  Can you help me figure out what I'm not doing to reproduce the crashing stack?

However, LayoutTests/inspector/layers/layers-compositing-reasons.html does reproduce the crash through different means.

[zalan]

Can't we just clamp the canvas size?

[Simon Fraser (smfr)]

Comment on attachment 294668 [details]
Patch v1

View in context: https://bugs.webkit.org/attachment.cgi?id=294668&action=review

> Source/WebCore/rendering/RenderLayerCompositor.cpp:2541
> +        bool isCanvasLargeEnoughToForceCompositing = canvasArea.hasOverflowed() || canvasArea.unsafeGet() >= canvasAreaThresholdRequiringCompositing;

I think we should avoid compositing if the area overflowed.

[David Kilzer (:ddkilzer)]

(In reply to comment #4)
> Can't we just clamp the canvas size?

What do you propose that we clamp it to without introducing compatibility issues?

Note that setWidth() and setHeight() in Source/WebCore/html/HTMLCanvasElement.cpp already call limitToOnlyHTMLNonNegative() in HTMLParserIdioms.h, which is maxHTMLNonNegativeInteger == 2147483647 == (2^31 - 1).

Also, we don't know of any other places where large canvas elements cause problems.

[David Kilzer (:ddkilzer)]

Created attachment 294709 [details]
Patch v2

[WebKit Commit Bot]

Comment on attachment 294709 [details]
Patch v2

Clearing flags on attachment: 294709

Committed r208691: <http://trac.webkit.org/changeset/208691>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.