Null deref, this is no a dev machine so I can't investigate further. Happens in the nightly from r198070. Process: com.apple.WebKit.WebContent.Development [6631] Path: /Volumes/VOLUME/WebKit.app/Contents/Frameworks/10-11/WebKit.framework/Versions/A/XPCServices/com.apple.WebKit.WebContent.Development.xpc/Contents/MacOS/com.apple.WebKit.WebContent.Development Identifier: com.apple.WebKit.WebContent.Development Version: 602+ (602.1.23+) Code Type: X86-64 (Native) Parent Process: ??? [1] Responsible: SafariForWebKitDevelopment [6578] User ID: 501 Date/Time: 2016-03-12 19:31:28.355 -0800 OS Version: Mac OS X 10.11.3 (15D21) Report Version: 11 Anonymous UUID: 1C46B275-63E4-0BB5-438C-B3E37CB8069F Time Awake Since Boot: 720000 seconds System Integrity Protection: enabled Crashed Thread: 0 Dispatch queue: com.apple.main-thread Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000005 Exception Note: EXC_CORPSE_NOTIFY VM Regions Near 0x5: --> __TEXT 0000000100163000-0000000100165000 [ 8K] r-x/rwx SM=COW /Volumes/VOLUME/WebKit.app/Contents/Frameworks/10-11/WebKit.framework/Versions/A/XPCServices/com.apple.WebKit.WebContent.Development.xpc/Contents/MacOS/com.apple.WebKit.WebContent.Development Application Specific Information: Bundle controller class: BrowserBundleController Process Model: Multiple Web Processes Global Trace Buffer (reverse chronological seconds): 0.679758 CFNetwork 0x00007fff99d2bd29 Explicitly setting CF cookie storage singleton 0.679995 CFNetwork 0x00007fff99d62621 Explicitly setting cookie storage singleton Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 com.apple.JavaScriptCore 0x000000010119053e JSC::JSObject::hasPropertyGeneric(JSC::ExecState*, JSC::PropertyName, JSC::PropertySlot::InternalMethodType) const + 2238 1 com.apple.JavaScriptCore 0x00000001012a896f JSC::toPropertyDescriptor(JSC::ExecState*, JSC::JSValue, JSC::PropertyDescriptor&) + 1471 2 com.apple.JavaScriptCore 0x00000001012a5aa0 JSC::objectConstructorDefineProperty(JSC::ExecState*) + 560 3 ??? 0x000050826fa01028 0 + 88521148731432 4 com.apple.JavaScriptCore 0x0000000101268a33 llint_entry + 23457 5 com.apple.JavaScriptCore 0x0000000101262caf vmEntryToJavaScript + 299 6 com.apple.JavaScriptCore 0x00000001010da9ae JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*) + 158 7 com.apple.JavaScriptCore 0x000000010103a99f JSC::Interpreter::executeCall(JSC::ExecState*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) + 447 8 com.apple.JavaScriptCore 0x0000000100c5846e JSC::call(JSC::ExecState*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) + 62 9 com.apple.JavaScriptCore 0x0000000100dd3d8d JSC::ProxyObject::performDefineOwnProperty(JSC::ExecState*, JSC::PropertyName, JSC::PropertyDescriptor const&, bool) + 1485 10 com.apple.JavaScriptCore 0x00000001012ae70e JSC::objectProtoFuncDefineGetter(JSC::ExecState*) + 958 11 ??? 0x000050826fa01028 0 + 88521148731432 12 com.apple.JavaScriptCore 0x0000000101268a33 llint_entry + 23457 13 com.apple.JavaScriptCore 0x0000000101268a33 llint_entry + 23457 14 com.apple.JavaScriptCore 0x0000000101268a33 llint_entry + 23457 15 com.apple.JavaScriptCore 0x0000000101262caf vmEntryToJavaScript + 299 16 com.apple.JavaScriptCore 0x00000001010da9ae JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*) + 158 17 com.apple.JavaScriptCore 0x000000010103a6bb JSC::Interpreter::execute(JSC::ProgramExecutable*, JSC::ExecState*, JSC::JSObject*) + 16619 18 com.apple.JavaScriptCore 0x0000000100cb3651 JSC::evaluate(JSC::ExecState*, JSC::SourceCode const&, JSC::JSValue, WTF::NakedPtr<JSC::Exception>&) + 593 19 com.apple.WebCore 0x0000000102615d65 WebCore::ScriptController::evaluateInWorld(WebCore::ScriptSourceCode const&, WebCore::DOMWrapperWorld&, WebCore::ExceptionDetails*) + 309 20 com.apple.WebCore 0x0000000102615fb0 WebCore::ScriptController::evaluate(WebCore::ScriptSourceCode const&, WebCore::ExceptionDetails*) + 48 21 com.apple.WebCore 0x000000010261c072 WebCore::ScriptElement::executeScript(WebCore::ScriptSourceCode const&) + 562 22 com.apple.WebCore 0x000000010261aae5 WebCore::ScriptElement::prepareScript(WTF::TextPosition const&, WebCore::ScriptElement::LegacyTypeSupport) + 1061 23 com.apple.WebCore 0x0000000101db48f8 WebCore::HTMLScriptRunner::runScript(WebCore::Element*, WTF::TextPosition const&) + 344 24 com.apple.WebCore 0x0000000101db4750 WebCore::HTMLScriptRunner::execute(WTF::PassRefPtr<WebCore::Element>, WTF::TextPosition const&) + 48 25 com.apple.WebCore 0x0000000101d4d44c WebCore::HTMLDocumentParser::runScriptsForPausedTreeBuilder() + 316 26 com.apple.WebCore 0x0000000101d4d7fb WebCore::HTMLDocumentParser::pumpTokenizerLoop(WebCore::HTMLDocumentParser::SynchronousMode, bool, WebCore::PumpSession&) + 667 27 com.apple.WebCore 0x0000000101d4d093 WebCore::HTMLDocumentParser::pumpTokenizer(WebCore::HTMLDocumentParser::SynchronousMode) + 115 28 com.apple.WebCore 0x0000000101d4e48e WebCore::HTMLDocumentParser::resumeParsingAfterScriptExecution() + 350 29 com.apple.WebCore 0x0000000101d4e682 WebCore::HTMLDocumentParser::notifyFinished(WebCore::CachedResource*) + 82 30 com.apple.WebCore 0x00000001018ee3a9 WebCore::CachedResource::checkNotify() + 153 31 com.apple.WebCore 0x000000010276bdd1 WebCore::SubresourceLoader::didFinishLoading(double) + 1153 32 com.apple.WebKit 0x000000010038b660 WebKit::WebResourceLoader::didReceiveWebResourceLoaderMessage(IPC::Connection&, IPC::MessageDecoder&) + 460 33 com.apple.WebKit 0x0000000100197ba1 IPC::Connection::dispatchMessage(std::__1::unique_ptr<IPC::MessageDecoder, std::__1::default_delete<IPC::MessageDecoder> >) + 127 34 com.apple.WebKit 0x000000010019a50a IPC::Connection::dispatchOneMessage() + 126 35 com.apple.JavaScriptCore 0x0000000101538a82 WTF::RunLoop::performWork() + 898 36 com.apple.JavaScriptCore 0x0000000101538c62 WTF::RunLoop::performWork(void*) + 34 37 com.apple.CoreFoundation 0x00007fff8eb6f5c1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 38 com.apple.CoreFoundation 0x00007fff8eb6141c __CFRunLoopDoSources0 + 556 39 com.apple.CoreFoundation 0x00007fff8eb6093f __CFRunLoopRun + 927 40 com.apple.CoreFoundation 0x00007fff8eb60338 CFRunLoopRunSpecific + 296 41 com.apple.HIToolbox 0x00007fff95f72935 RunCurrentEventLoopInMode + 235 42 com.apple.HIToolbox 0x00007fff95f7276f ReceiveNextEventCommon + 432 43 com.apple.HIToolbox 0x00007fff95f725af _BlockUntilNextEventMatchingListInModeWithFilter + 71 44 com.apple.AppKit 0x00007fff8bcfd0ee _DPSNextEvent + 1067 45 com.apple.AppKit 0x00007fff8c0c9943 -[NSApplication _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 454 46 com.apple.AppKit 0x00007fff8bcf2fc8 -[NSApplication run] + 682 47 com.apple.AppKit 0x00007fff8bc75520 NSApplicationMain + 1176 48 libxpc.dylib 0x00007fff9b84ff6c _xpc_objc_main + 793 49 libxpc.dylib 0x00007fff9b8516bb xpc_main + 494 50 com.apple.WebKit.WebContent.Development 0x00000001001647df main + 422 51 libdyld.dylib 0x00007fff96a3f5ad start + 1 Thread 1: 0 libsystem_kernel.dylib 0x00007fffa01136de __workq_kernreturn + 10 1 libsystem_pthread.dylib 0x00007fff8cb6a729 _pthread_wqthread + 1283 2 libsystem_pthread.dylib 0x00007fff8cb68365 start_wqthread + 13 Thread 2:: Dispatch queue: com.apple.libdispatch-manager 0 libsystem_kernel.dylib 0x00007fffa0113ff6 kevent_qos + 10 1 libdispatch.dylib 0x00007fff8fcb5099 _dispatch_mgr_invoke + 216 2 libdispatch.dylib 0x00007fff8fcb4d01 _dispatch_mgr_thread + 52 Thread 3: 0 libsystem_kernel.dylib 0x00007fffa01136de __workq_kernreturn + 10 1 libsystem_pthread.dylib 0x00007fff8cb6a729 _pthread_wqthread + 1283 2 libsystem_pthread.dylib 0x00007fff8cb68365 start_wqthread + 13 Thread 4: 0 libsystem_kernel.dylib 0x00007fffa01136de __workq_kernreturn + 10 1 libsystem_pthread.dylib 0x00007fff8cb6a729 _pthread_wqthread + 1283 2 libsystem_pthread.dylib 0x00007fff8cb68365 start_wqthread + 13 Thread 5: 0 libsystem_kernel.dylib 0x00007fffa01136de __workq_kernreturn + 10 1 libsystem_pthread.dylib 0x00007fff8cb6a729 _pthread_wqthread + 1283 2 libsystem_pthread.dylib 0x00007fff8cb68365 start_wqthread + 13 Thread 6: Thread 7:: com.apple.NSEventThread 0 libsystem_kernel.dylib 0x00007fffa010d386 mach_msg_trap + 10 1 libsystem_kernel.dylib 0x00007fffa010c7c7 mach_msg + 55 2 com.apple.CoreFoundation 0x00007fff8eb61624 __CFRunLoopServiceMachPort + 212 3 com.apple.CoreFoundation 0x00007fff8eb60aec __CFRunLoopRun + 1356 4 com.apple.CoreFoundation 0x00007fff8eb60338 CFRunLoopRunSpecific + 296 5 com.apple.AppKit 0x00007fff8bdbc065 _NSEventThread + 149 6 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 7 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 8 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 8:: com.apple.NSURLConnectionLoader 0 libsystem_kernel.dylib 0x00007fffa010d386 mach_msg_trap + 10 1 libsystem_kernel.dylib 0x00007fffa010c7c7 mach_msg + 55 2 com.apple.CoreFoundation 0x00007fff8eb61624 __CFRunLoopServiceMachPort + 212 3 com.apple.CoreFoundation 0x00007fff8eb60aec __CFRunLoopRun + 1356 4 com.apple.CoreFoundation 0x00007fff8eb60338 CFRunLoopRunSpecific + 296 5 com.apple.CFNetwork 0x00007fff99b656e9 +[NSURLConnection(Loader) _resourceLoadLoop:] + 412 6 com.apple.Foundation 0x00007fff958d4c6f __NSThread__start__ + 1351 7 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 8 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 9 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 9: 0 libsystem_kernel.dylib 0x00007fffa0113206 __semwait_signal + 10 1 libsystem_c.dylib 0x00007fff8ce16d17 nanosleep + 199 2 libc++.1.dylib 0x00007fff9a817020 std::__1::this_thread::sleep_for(std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > const&) + 75 3 com.apple.JavaScriptCore 0x00000001015578cb bmalloc::Heap::scavenge(std::__1::unique_lock<bmalloc::StaticMutex>&, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000l> >) + 155 4 com.apple.JavaScriptCore 0x0000000101557804 bmalloc::Heap::concurrentScavenge() + 68 5 com.apple.JavaScriptCore 0x000000010155940a bmalloc::AsyncTask<bmalloc::Heap, void (bmalloc::Heap::*)()>::threadRunLoop() + 90 6 com.apple.JavaScriptCore 0x000000010155962d void* std::__1::__thread_proxy<std::__1::tuple<void (*)(bmalloc::AsyncTask<bmalloc::Heap, void (bmalloc::Heap::*)()>*), bmalloc::AsyncTask<bmalloc::Heap, void (bmalloc::Heap::*)()>*> >(void*) + 93 7 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 8 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 9 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 10:: WebCore: Scrolling 0 libsystem_kernel.dylib 0x00007fffa010d386 mach_msg_trap + 10 1 libsystem_kernel.dylib 0x00007fffa010c7c7 mach_msg + 55 2 com.apple.CoreFoundation 0x00007fff8eb61624 __CFRunLoopServiceMachPort + 212 3 com.apple.CoreFoundation 0x00007fff8eb60aec __CFRunLoopRun + 1356 4 com.apple.CoreFoundation 0x00007fff8eb60338 CFRunLoopRunSpecific + 296 5 com.apple.CoreFoundation 0x00007fff8ec231f1 CFRunLoopRun + 97 6 com.apple.WebCore 0x0000000102638d5d WebCore::ScrollingThread::initializeRunLoop() + 253 7 com.apple.JavaScriptCore 0x0000000101548cd2 WTF::threadEntryPoint(void*) + 178 8 com.apple.JavaScriptCore 0x00000001015490ef WTF::wtfThreadEntryPoint(void*) + 15 9 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 10 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 11 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 11:: WTF Parallel Helper Thread 0 libsystem_kernel.dylib 0x00007fffa0112eb2 __psynch_cvwait + 10 1 libsystem_pthread.dylib 0x00007fff8cb6b150 _pthread_cond_wait + 767 2 libc++.1.dylib 0x00007fff9a7d868f std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 47 3 com.apple.JavaScriptCore 0x0000000101536e3e WTF::ParkingLot::parkConditionally(void const*, std::__1::function<bool ()>, std::__1::function<void ()>, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 2494 4 com.apple.JavaScriptCore 0x0000000100eed0fa bool WTF::ConditionBase::waitUntil<WTF::Lock>(WTF::Lock&, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 154 5 com.apple.JavaScriptCore 0x0000000101536253 WTF::ParallelHelperPool::waitForClientWithTask(WTF::Locker<WTF::LockBase> const&) + 291 6 com.apple.JavaScriptCore 0x0000000101536013 WTF::ParallelHelperPool::helperThreadBody() + 83 7 com.apple.JavaScriptCore 0x0000000101548cd2 WTF::threadEntryPoint(void*) + 178 8 com.apple.JavaScriptCore 0x00000001015490ef WTF::wtfThreadEntryPoint(void*) + 15 9 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 10 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 11 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 12:: WTF Parallel Helper Thread 0 libsystem_kernel.dylib 0x00007fffa0112eb2 __psynch_cvwait + 10 1 libsystem_pthread.dylib 0x00007fff8cb6b150 _pthread_cond_wait + 767 2 libc++.1.dylib 0x00007fff9a7d868f std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 47 3 com.apple.JavaScriptCore 0x0000000101536e3e WTF::ParkingLot::parkConditionally(void const*, std::__1::function<bool ()>, std::__1::function<void ()>, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 2494 4 com.apple.JavaScriptCore 0x0000000100eed0fa bool WTF::ConditionBase::waitUntil<WTF::Lock>(WTF::Lock&, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 154 5 com.apple.JavaScriptCore 0x0000000101536253 WTF::ParallelHelperPool::waitForClientWithTask(WTF::Locker<WTF::LockBase> const&) + 291 6 com.apple.JavaScriptCore 0x0000000101536013 WTF::ParallelHelperPool::helperThreadBody() + 83 7 com.apple.JavaScriptCore 0x0000000101548cd2 WTF::threadEntryPoint(void*) + 178 8 com.apple.JavaScriptCore 0x00000001015490ef WTF::wtfThreadEntryPoint(void*) + 15 9 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 10 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 11 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 13:: WTF Parallel Helper Thread 0 libsystem_kernel.dylib 0x00007fffa0112eb2 __psynch_cvwait + 10 1 libsystem_pthread.dylib 0x00007fff8cb6b150 _pthread_cond_wait + 767 2 libc++.1.dylib 0x00007fff9a7d868f std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 47 3 com.apple.JavaScriptCore 0x0000000101536e3e WTF::ParkingLot::parkConditionally(void const*, std::__1::function<bool ()>, std::__1::function<void ()>, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 2494 4 com.apple.JavaScriptCore 0x0000000100eed0fa bool WTF::ConditionBase::waitUntil<WTF::Lock>(WTF::Lock&, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 154 5 com.apple.JavaScriptCore 0x0000000101536253 WTF::ParallelHelperPool::waitForClientWithTask(WTF::Locker<WTF::LockBase> const&) + 291 6 com.apple.JavaScriptCore 0x0000000101536013 WTF::ParallelHelperPool::helperThreadBody() + 83 7 com.apple.JavaScriptCore 0x0000000101548cd2 WTF::threadEntryPoint(void*) + 178 8 com.apple.JavaScriptCore 0x00000001015490ef WTF::wtfThreadEntryPoint(void*) + 15 9 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 10 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 11 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 14:: WTF Parallel Helper Thread 0 libsystem_kernel.dylib 0x00007fffa0112eb2 __psynch_cvwait + 10 1 libsystem_pthread.dylib 0x00007fff8cb6b150 _pthread_cond_wait + 767 2 libc++.1.dylib 0x00007fff9a7d868f std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 47 3 com.apple.JavaScriptCore 0x0000000101536e3e WTF::ParkingLot::parkConditionally(void const*, std::__1::function<bool ()>, std::__1::function<void ()>, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 2494 4 com.apple.JavaScriptCore 0x0000000100eed0fa bool WTF::ConditionBase::waitUntil<WTF::Lock>(WTF::Lock&, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 154 5 com.apple.JavaScriptCore 0x0000000101536253 WTF::ParallelHelperPool::waitForClientWithTask(WTF::Locker<WTF::LockBase> const&) + 291 6 com.apple.JavaScriptCore 0x0000000101536013 WTF::ParallelHelperPool::helperThreadBody() + 83 7 com.apple.JavaScriptCore 0x0000000101548cd2 WTF::threadEntryPoint(void*) + 178 8 com.apple.JavaScriptCore 0x00000001015490ef WTF::wtfThreadEntryPoint(void*) + 15 9 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 10 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 11 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 15:: WTF Parallel Helper Thread 0 libsystem_kernel.dylib 0x00007fffa0112eb2 __psynch_cvwait + 10 1 libsystem_pthread.dylib 0x00007fff8cb6b150 _pthread_cond_wait + 767 2 libc++.1.dylib 0x00007fff9a7d868f std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 47 3 com.apple.JavaScriptCore 0x0000000101536e3e WTF::ParkingLot::parkConditionally(void const*, std::__1::function<bool ()>, std::__1::function<void ()>, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 2494 4 com.apple.JavaScriptCore 0x0000000100eed0fa bool WTF::ConditionBase::waitUntil<WTF::Lock>(WTF::Lock&, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 154 5 com.apple.JavaScriptCore 0x0000000101536253 WTF::ParallelHelperPool::waitForClientWithTask(WTF::Locker<WTF::LockBase> const&) + 291 6 com.apple.JavaScriptCore 0x0000000101536013 WTF::ParallelHelperPool::helperThreadBody() + 83 7 com.apple.JavaScriptCore 0x0000000101548cd2 WTF::threadEntryPoint(void*) + 178 8 com.apple.JavaScriptCore 0x00000001015490ef WTF::wtfThreadEntryPoint(void*) + 15 9 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 10 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 11 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 16:: WTF Parallel Helper Thread 0 libsystem_kernel.dylib 0x00007fffa0112eb2 __psynch_cvwait + 10 1 libsystem_pthread.dylib 0x00007fff8cb6b150 _pthread_cond_wait + 767 2 libc++.1.dylib 0x00007fff9a7d868f std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 47 3 com.apple.JavaScriptCore 0x0000000101536e3e WTF::ParkingLot::parkConditionally(void const*, std::__1::function<bool ()>, std::__1::function<void ()>, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 2494 4 com.apple.JavaScriptCore 0x0000000100eed0fa bool WTF::ConditionBase::waitUntil<WTF::Lock>(WTF::Lock&, std::__1::chrono::time_point<std::__1::chrono::steady_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) + 154 5 com.apple.JavaScriptCore 0x0000000101536253 WTF::ParallelHelperPool::waitForClientWithTask(WTF::Locker<WTF::LockBase> const&) + 291 6 com.apple.JavaScriptCore 0x0000000101536013 WTF::ParallelHelperPool::helperThreadBody() + 83 7 com.apple.JavaScriptCore 0x0000000101548cd2 WTF::threadEntryPoint(void*) + 178 8 com.apple.JavaScriptCore 0x00000001015490ef WTF::wtfThreadEntryPoint(void*) + 15 9 libsystem_pthread.dylib 0x00007fff8cb6ac13 _pthread_body + 131 10 libsystem_pthread.dylib 0x00007fff8cb6ab90 _pthread_start + 168 11 libsystem_pthread.dylib 0x00007fff8cb68375 thread_start + 13 Thread 0 crashed with X86 Thread State (64-bit): rax: 0x0000000107a5ad58 rbx: 0x0000000000000001 rcx: 0x0000000023a41e65 rdx: 0x0000000000000000 rdi: 0x0000000000000010 rsi: 0x00000001083b6ea0 rbp: 0x00007fff5fa99800 rsp: 0x00007fff5fa99770 r8: 0x00000001083b6ee0 r9: 0x0000000000000000 r10: 0x000000000000000f r11: 0xffff000000000002 r12: 0x0000000107a5ad40 r13: 0x0000000108231080 r14: 0x0000000000000000 r15: 0x0000000107bb2120 rip: 0x000000010119053e rfl: 0x0000000000010246 cr2: 0x0000000000000005 Logical CPU: 6 Error Code: 0x00000004 Trap Number: 14
<rdar://problem/25131391>
Here's a more descriptive crash trace using a debug build: ASSERTION FAILED: descriptor.setter() /Volumes/Data/ws4/OpenSource/Source/JavaScriptCore/runtime/ObjectConstructor.h(108) : JSC::JSObject *JSC::constructObjectFromPropertyDescriptor(JSC::ExecState *, const JSC::PropertyDescriptor &) 1 0x1056cae00 WTFCrash 2 0x104cd9bc3 JSC::constructObjectFromPropertyDescriptor(JSC::ExecState*, JSC::PropertyDescriptor const&) 3 0x104cd6f57 JSC::ProxyObject::performDefineOwnProperty(JSC::ExecState*, JSC::PropertyName, JSC::PropertyDescriptor const&, bool) 4 0x104cd2216 JSC::ProxyObject::defineOwnProperty(JSC::JSObject*, JSC::ExecState*, JSC::PropertyName, JSC::PropertyDescriptor const&, bool) 5 0x105372381 JSC::objectProtoFuncDefineGetter(JSC::ExecState*) 6 0x4723a0201028 7 0x1052f7fc5 llint_entry The issue is that constructObjectFromPropertyDescriptor() is expecting that when the descriptor is an accessor, that both the getter and setter are defined. In this case, the getter is, but the setter is not. The crash comes from using the null setter in the descriptor.
Created attachment 273874 [details] proposed patch. Currently running tests.
Comment on attachment 273874 [details] proposed patch. r=me
Thanks for the review. Landed in r198080: <http://trac.webkit.org/r198080>.