1749819 - MOZ_ASSERT failure in mozJSSubScriptLoader::ReadStencil

Status: RESOLVED FIXED

(Core :: XPConnect, defect)

Description

[Micah [:mtigley] (she/her)]

Found this while trying to load a subscript with a "moz-extension" URL into a child actor. I'm getting the following failure on a recent try push.

This is caused by this assertion failing: https://searchfox.org/mozilla-central/rev/83e67336083df9f9a3d1e0c33f2ba19703d57161/js/xpconnect/loader/mozJSSubScriptLoader.cpp#264. This seems to suggests the channel somehow isn't being updated with the new content length by NS_ReadInputStreamToString().

It's not clear to me where the update should happen in NS_ReadInputStreamToString() though.

Comment 1

[Micah [:mtigley] (she/her)]

Attachment: Bug 1749819 - Remove check for channel GetContentLength(). r=#dom-workers-and-storage-reviewers

Depends on D109073

Comment 2

[Rob Wu [:robwu]]

Minimal test case based on the original test case:

1. ./mach run --temp-profile.
2. Visit example.com and open the Browser Content Toolbox.
3. Run the following snippet:

{
  let { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
  let { WebExtensionPolicy } = Cu.getGlobalForObject(Services);
  let url = WebExtensionPolicy.getByID("[e-mail]").getURL("run.js");
  Services.scriptloader.loadSubScript(url, sandbox);
}

Expected output:

• Uncaught ReferenceError: PictureInPictureOverrides is not defined

Actual result:

• content process crashes with the following:

Assertion failure: currentLength == len, at /builds/worker/checkouts/gecko/js/xpconnect/loader/mozJSSubScriptLoader.cpp:264
#01: mozJSSubScriptLoader::ReadStencil(js::frontend::CompilationStencil**, nsIURI*, JSContext*, JS::ReadOnlyCompileOptions const&, nsIIOService*, bool)[/path/to/dist/NightlyDebug.app/Contents/MacOS/XUL +0x109f405]
#02: mozJSSubScriptLoader::DoLoadSubScriptWithOptions(nsTSubstring<char16_t> const&, LoadSubScriptOptions&, JSContext*, JS::MutableHandle<JS::Value>)[/path/to/dist/NightlyDebug.app/Contents/MacOS/XUL +0x10a03bc]
#03: mozJSSubScriptLoader::LoadSubScript(nsTSubstring<char16_t> const&, JS::Handle<JS::Value>, JSContext*, JS::MutableHandle<JS::Value>)[/path/to/dist/NightlyDebug.app/Contents/MacOS/XUL +0x109f78e]
#04: NS_InvokeByIndex[/path/to/dist/NightlyDebug.app/Contents/MacOS/XUL +0x33c30e]

This only happens in the content process; the moz-extension:-protocol handler uses a SimpleChannel to retrieve the actual content from the parent.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/398dbd0b53ce
Remove check for channel GetContentLength(). r=dom-workers-and-storage-reviewers,mccr8,asuth

Comment 4

[Marian-Vasile Laza]

https://hg.mozilla.org/mozilla-central/rev/398dbd0b53ce