Bug 257091 – Crash when GC finalizes ErrorInstance when allocating very long JSString*

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Jarred Sumner]

Stack trace:

```
WTFCrashWithInfo(int, char const*, char const*, int) (/Users/jarred/Code/bun/node_modules/bun-webkit-macos-arm64/include/wtf/Assertions.h:758)
JSC::LocalAllocator::allocateSlowCase(JSC::Heap&, unsigned long, JSC::GCDeferralContext*, JSC::AllocationFailureMode) (@JSC::LocalAllocator::allocateSlowCase(JSC::Heap&, unsigned long, JSC::GCDeferralContext*, JSC::AllocationFailureMode):67)
JSC::LocalAllocator::allocate(JSC::Heap&, unsigned long, JSC::GCDeferralContext*, JSC::AllocationFailureMode)::'lambda'()::operator()() const (/Users/jarred/Code/bun/node_modules/bun-webkit-macos-arm64/include/JavaScriptCore/LocalAllocatorInlines.h:41)
JSC::HeapCell* JSC::FreeList::allocateWithCellSize<JSC::LocalAllocator::allocate(JSC::Heap&, unsigned long, JSC::GCDeferralContext*, JSC::AllocationFailureMode)::'lambda'()>(JSC::LocalAllocator::allocate(JSC::Heap&, unsigned long, JSC::GCDeferralContext*, JSC::AllocationFailureMode)::'lambda'() const&, unsigned long) (/Users/jarred/Code/bun/node_modules/bun-webkit-macos-arm64/include/JavaScriptCore/FreeListInlines.h:44)
JSC::LocalAllocator::allocate(JSC::Heap&, unsigned long, JSC::GCDeferralContext*, JSC::AllocationFailureMode) (/Users/jarred/Code/bun/node_modules/bun-webkit-macos-arm64/include/JavaScriptCore/LocalAllocatorInlines.h:38)
JSC::GCClient::IsoSubspace::allocate(JSC::VM&, unsigned long, JSC::GCDeferralContext*, JSC::AllocationFailureMode) (/Users/jarred/Code/bun/node_modules/bun-webkit-macos-arm64/include/JavaScriptCore/IsoSubspaceInlines.h:34)
void* JSC::tryAllocateCellHelper<JSC::JSString, (JSC::AllocationFailureMode)0>(JSC::VM&, unsigned long, JSC::GCDeferralContext*) (/Users/jarred/Code/bun/node_modules/bun-webkit-macos-arm64/include/JavaScriptCore/JSCellInlines.h:190)
void* JSC::allocateCell<JSC::JSString>(JSC::VM&, unsigned long) (/Users/jarred/Code/bun/node_modules/bun-webkit-macos-arm64/include/JavaScriptCore/JSCellInlines.h:206)
JSC::JSString::create(JSC::VM&, WTF::Ref<WTF::StringImpl, WTF::RawPtrTraits<WTF::StringImpl>>&&) (/Users/jarred/Code/bun/node_modules/bun-webkit-macos-arm64/include/JavaScriptCore/JSString.h:187)
JSC::JSFunction::originalName(JSC::JSGlobalObject*) (@JSC::JSFunction::originalName(JSC::JSGlobalObject*):253)
JSC::JSBoundFunction::nameSlow(JSC::VM&) (@JSC::JSBoundFunction::nameSlow(JSC::VM&):47)
JSC::JSFunction::name(JSC::VM&) (@JSC::JSFunction::name(JSC::VM&):58)
JSC::getCalculatedDisplayName(JSC::VM&, JSC::JSObject*) (@JSC::getCalculatedDisplayName(JSC::VM&, JSC::JSObject*):65)
JSC::StackFrame::functionName(JSC::VM&) const (@JSC::StackFrame::functionName(JSC::VM&) const:43)
JSC::StackFrame::toString(JSC::VM&) const (@JSC::StackFrame::toString(JSC::VM&) const:13)
JSC::Interpreter::stackTraceAsString(JSC::VM&, WTF::Vector<JSC::StackFrame, 0ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc> const&) (@JSC::Interpreter::stackTraceAsString(JSC::VM&, WTF::Vector<JSC::StackFrame, 0ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc> const&):35)
JSC::ErrorInstance::computeErrorInfo(JSC::VM&) (@JSC::ErrorInstance::computeErrorInfo(JSC::VM&):23)
JSC::Heap::finalizeUnconditionalFinalizers() (@JSC::Heap::finalizeUnconditionalFinalizers():306)
JSC::Heap::runEndPhase(JSC::GCConductor) (@JSC::Heap::runEndPhase(JSC::GCConductor):355)
JSC::Heap::runCurrentPhase(JSC::GCConductor, JSC::CurrentThreadState*) (@JSC::Heap::runCurrentPhase(JSC::GCConductor, JSC::CurrentThreadState*):97)
WTF::ScopedLambdaFunctor<void (JSC::CurrentThreadState&), JSC::Heap::collectInMutatorThread()::$_25>::implFunction(void*, JSC::CurrentThreadState&) (@WTF::ScopedLambdaFunctor<void (JSC::CurrentThreadState&), JSC::Heap::collectInMutatorThread()::$_25>::implFunction(void*, JSC::CurrentThreadState&):12)
JSC::callWithCurrentThreadState(WTF::ScopedLambda<void (JSC::CurrentThreadState&)> const&) (@JSC::callWithCurrentThreadState(WTF::ScopedLambda<void (JSC::CurrentThreadState&)> const&):45)
JSC::Heap::collectInMutatorThread() (@JSC::Heap::collectInMutatorThread():27)
JSC::Heap::waitForCollection(unsigned long long) (@JSC::Heap::waitForCollection(unsigned long long):42)
JSC::Heap::collectSync(JSC::GCRequest) (@JSC::Heap::collectSync(JSC::GCRequest):30)
```

Still trying to reproduce in JSC shell

Here is code which **does not reproduce it** (I tried a variation that imported it in another file, called Loader.registry.clear() and that didn't reproduce it either)

```
const gc = globalThis.fullGC || (() => Bun.gc(true));

// import { bench, run } from "../../node_modules/mitata/src/cli.mjs";

globalThis.a = 0;
const count = 1000;
Error.stackTraceLimit = 100;
globalThis.veryLongName = "super long name".repeat(999_999).split("").join("");
for (let i = 0; i < count; i++) {
  (function () {
    var errors = new Array(count);
    globalThis.errors = errors;

    try {
      globalThis.a = 0;
      eval(`

var veryLongFunctionA;

veryLongFunctionA = function veryLongFunctionName(remaining) {
  if (remaining-- === 0) {
    var capturedStack;
    try {
        throw new Error();
    } catch(e) {
        capturedStack = e.stack;
    }
    throw new Error("i threw! " + veryLongName);
  }
  globalThis.a += 1;  
  return veryLongFunction(remaining, undefined);
};


globalThis.veryLongFunctionA = veryLongFunctionA;
Object.defineProperty(veryLongFunction = veryLongFunction.bind(undefined), "name", {
    value: "veryLongFunction" + veryLongName,
    configurable: true,
    writable: true,
  });

globalThis.veryLongFunction = veryLongFunction;
var j = 0;
var veryLongFunction = veryLongFunctionA;
veryLongFunction(1000);
`);
    } catch (e) {
      errors.push(e);
    }

    delete globalThis.errors;
  })();
  gc();
}
```


More context: https://github.com/oven-sh/bun/issues/198#issuecomment-1555961906

[Yusuke Suzuki]

rdar://109614514

[Yusuke Suzuki]

Pull request: https://github.com/WebKit/WebKit/pull/14148

[EWS]

Committed 264299@main (8661025c07ae): <https://commits.webkit.org/264299@main>

Reviewed commits have been landed. Closing PR #14148 and removing active labels.