Found in

• Firefox 110.0a1 (BuildId:20230105092304)

Affected versions

• Firefox 110.0a1 (BuildId:20230105092304)

Tested platforms

• Affected platforms: All Windows .
• Unaffected platforms: macOS & Ubuntu.

Preconditions

• Have Google Drive for desktop installed (https://www.google.com/drive/download/) or TortoiseGit (https://tortoisegit.org/) installed.

Steps to reproduce

1. Access the about:third-party page.
2. Hit CTRL + O.
3. Close the File Explorer and refresh the about:third-party page.
4. Block the drivefsext.dll or the TortoiseOverlays.dll.
5. Click on "Restart Nightly now" when prompted.
6. Unblock the TestDllBlocklist_UserBlocked.dll.
7. Click on "Restart Nightly now" when prompted.
8. Hit CTRL + O & access the Google drive location (if the drivefsext.dll was blocked) or a file where a git repository was initialized (if the TortoiseOverlays.dll was blocked).
9. Close the File Explorer and refresh the about:third-party page.

Expected result

• Step 8: The dll which was blocked in step 4 is successfully blocked (the overlay is not displayed on files for that particular service).
• Step 9: The dll's name is successfully displayed inside the about:third-party page.

Actual result

• Step 8: The dll which was blocked in step 4 is not actually blocked (the overlay is displayed on files for that particular service).
• Step 9: The dll's name is not parsed correctly.

Regression range

• This is not a regression.

Additional Notes
Copying the raw data to clipboard from the about:third-party page gives me the following output when this issue is reproduced:

"blocked": [ "TestDllBlocklist_UserBlocked.dll", "\u0000rivefsext.dll" ]

I think that the issue described in comment 0 is similar to another symptom (please let me know if we should indeed need to isolate this scenarios in a separate bug) which was encountered if:

If we are blocking both dll's at step 4 and then proceed to unblock the TestDllBlocklist_UserBlocked.dll the name of the last blocked dll (from step 4) is displayed (incorrectly) under the TestDllBlocklist_UserBlocked.dll with the status of "blocked" (but the dll is not actually blocked) (see screencast "v1")

And even worse, if continuing to yet again try to unblock the TestDllBlocklist_UserBlocked.dll while the issue mentioned in comment 2 is reproduced, both previously blocked dll's (TortoiseGit.dll and drivefsext.dll) are incorrectly displayed under TestDllBlocklist_UserBlocked.dll as being blocked (but the dll's are not actually blocked).

(see screencast "v2")

Once this releases I don't expect TestDllBlocklist_UserBlocked.dll to show up, but the fact that we're getting some sort of string corruption or something is very worrying.

This was causing the written blocklist to be one entry too small if the test entry was unblocked. (even though unblocking it wouldn't really do anything, as it would be reactivated on the next launch)

https://hg.mozilla.org/mozilla-central/rev/7cb56b6eb347

This issue is partially fixed using Firefox 110.0a1 (BuildId:20230106095123).

The name is no longer incorrectly displayed inside the about:third-party page but we are still hitting the scenario where other dll's are getting unblocked while trying to unblock the TestDllBlocklist_UserBlocked.dll (https://bugzilla.mozilla.org/show_bug.cgi?id=1808904#c1).

I think that we can close this and track that unwanted dll unblock scenario in Bug 1808904.