1987782 - PDF.js regression: unable to decode image when Resist Fingerprinting (RFP) is enabled

Status: RESOLVED DUPLICATE of bug 1977576

(Core :: Privacy: Anti-Tracking, defect, P3)

Description

[firefoxbugs]

Attachment: example file

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0

Steps to reproduce:

1. Enable Resist Fingerprinting (RFP) (In about:config set privacy.resistFingerprinting to true.)
2. Load the attached PDF file.

Actual results:

The picture in the PDF file does not appear.

Expected results:

Pictures should appear, as they did in Firefox 141 and earlier. This regression appears as early as 142.0b1.
The relevant console warning is this:
Warning: Unable to decode image "img_p0_1": "DataCloneError: DedicatedWorkerGlobalScope.postMessage: invalid transferable array for structured clone". pdf.worker.mjs:327:13

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Privacy: Anti-Tracking' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Giorgio Maone [:ma1]]

Reported to Tor as https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/44334

Comment 3

[Pier Angelo Vendrame]

2025-08-13-09-10-44, still broken --> https://hg.mozilla.org/mozilla-central/rev/6c51cabb2e48997969eb68ba245067238fbe46ec --> 782b850cc3fcf5c2be804914975488dc56c53db5 on git
2025-08-13-21-49-47, fixed --> https://hg.mozilla.org/mozilla-central/rev/968f84606bec92dde86792ba14b542a0594c5dcf --> 16b54290d0fee11b69885d31ff0188c8ff81e330 on git
I'm going to bisect locally.

Comment 4

[Pier Angelo Vendrame]

It seems the fix was 385990abc503da33309bbf047f9ed4880fe289c0, i.e., Bug 1977576.