• Dan Clark's avatar
    Make IsolateData::ModuleResolveCallback throw if module was not found · 13bf4f38
    Dan Clark authored
    The callback IsolateData::ModuleResolveCallback, used by the fuzzer,
    can return an empty MaybeLocal.
    In this case v8::internal::SourceTextModule::PrepareInstantiate expects
    it to have thrown an exception, and DCHECKs.
    
    The fuzzer can hit this case because it doesn't load the entire module
    graph before starting to tell V8 to instantiate modules. So if a module
    fails to compile or load, another module trying to import it will hit
    this DCHECK because we didn't bail out prior to module instantiation
    like we should have.
    
    This doesn't happen in Chromium because Blink loads the entire module
    graph before trying to instantiate/link modules, ensuring that the
    'real' ModuleRecord::ResolveModuleCallback never fails; indeed this is
    mandated by the spec (see
    https://html.spec.whatwg.org/#fetch-the-descendants-of-and-link-a-module-script).
    
    To satisfy the fuzzer, this change makes
    IsolateData::ModuleResolveCallback throw if it can't find the module.
    
    Note, the bug's testcase doesn't involve import assertions. I don't
    think this issue is new with my change
    https://chromium.googlesource.com/v8/v8/+/9d72d08a8c74d48eed53f742aebd56a5076cb8dd
    but maybe that changed the crash stack or something in a way that
    caused the issue to be reported.
    
    Bug: chromium:1207078
    Change-Id: I1fbc80faa099e040cdc489c965a5f2f5daafb38e
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2890589Reviewed-by: 's avatarMarja Hölttä <marja@chromium.org>
    Commit-Queue: Dan Clark <daniec@microsoft.com>
    Cr-Commit-Position: refs/heads/master@{#74526}
    13bf4f38
isolate-data.cc 18.8 KB