1630750 - "Clear Flash Cookies" extension no longer clears Flash plugin data (removePluginData) on Firefox startup

Status: RESOLVED INCOMPLETE

(WebExtensions :: General, defect, P5)

Description

[Chris Peterson [:cpeterson]]

I wrote a "Clear Flash Cookies" extension to delete Flash "super cookies" (Local Shared Objects). The extension calls the browsingData.removePluginData() WebExtension API in three different cases:

1. When the extension is enabled (either on first installation or re-enabled).
2. When the last open window is closed. That's easy to do on Mac. On Windows, closing the last window quits the app. You can work around that by opening the Browser Console window and then closing all the other browser windows.
3. On Firefox startup (after a three second delay to avoid janking startup).

removePluginData() works correctly for case #1 and #2, but not #3 on startup. I don't know if this is a problem specifically with removePluginData() on startup or a general problem about running extension code during startup. This could also be a Flash Player bug during Firefox or plugin process startup.

My extension's code is on GitHub:
https://github.com/cpeterso/clear-flash-cookies/blob/master/src/background.js

Steps to reproduce

1. Load Adobe's Flash Settings Manager page to view and delete any pre-existing Shared Objects.
2. Load permadi.com's Flash Shared Object demo and run the Flash content to write and read some Shared Objects.
3. Re-load Adobe's Flash Settings Manager page to see the new "permadi.com" Shared Object.
4. Now install my "Clear Flash Cookies" extension.
5. Re-load Adobe's Flash Settings Manager and you will see the "permadi.com" Shared Object has been deleted.
6. Re-load permadi.com's Flash Shared Object demo and create a new Shared Object.
7. Re-load Adobe's Flash Settings Manager and you will see the "permadi.com" Shared Object has been recreated.
8. Quit and restart Firefox.
9. Re-load Adobe's Flash Settings Manager.

Expected result

The "permadi.com" Shared Object should have been auto-deleted three seconds after Firefox startup.

Actual result

The "pemadi.com" Shared Object still exists.

Comment 1

[Release mgmt bot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 2

[Chris Peterson [:cpeterson]]

(In reply to Release mgmt bot [:sylvestre / :calixte / :marco for bugbug] from comment #1)

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

I think this bug first needs some WebExtension investigation of extension startup initialization before concluding it's a Plug-ins bug. Moving back to the WebExtensions component from Core::Plugin-ins.

Comment 3

[Augusto Pace]

Hi,

I was able to reproduce this issue on Windows 10 with Firefox version Nightly 77.0a1 (2020-04-21) (64-bit) - Beta 76.0b6 (64-bit) - Release 75.0 (64-bit). I'm setting component to WebExtensions - General.

Thanks.

Comment 4

[Tomislav Jovanovic :zombie]

Augusto, can you please find the regression window for this?

Comment 5

[Tomislav Jovanovic :zombie]

Krupa, can you please forward this to the right person.

Comment 6

[Chris Peterson [:cpeterson]]

Note that Firefox will EOL Flash plugin support in December 2020 (Firefox 84). If this bug is only about Firefox or Flash not deleting plugin data, fixing it is probably not worth the trouble. But we should probably first verify that this bug is not a general problem when trying to run extension code during Firefox startup.

Comment 7

[krupa raj [:krupa--use this to needinfo]]

Alex, can you take a look pls? Thanks

Comment 8

[Victor Carciu]

Hello ,

I performed a bisection for this issue with the following results :

pushlog_url: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=f69698a5cc46d070a64e8221a68a23da81708d66&tochange=bd8ef39cfadc0e427b1261ae8b2b2f7677d85bd2

2020-05-18T15:04:17: DEBUG : Found commit message:
Bug 1541344 - Delete plugin-data only for the sites with data,r=gsvelto

Thanks,
Victor

Comment 9

[Chris Peterson [:cpeterson]]

(In reply to Victor Carciu from comment #8)

I performed a bisection for this issue with the following results :

pushlog_url: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=f69698a5cc46d070a64e8221a68a23da81708d66&tochange=bd8ef39cfadc0e427b1261ae8b2b2f7677d85bd2

2020-05-18T15:04:17: DEBUG : Found commit message:
Bug 1541344 - Delete plugin-data only for the sites with data,r=gsvelto

Thanks, Victor! That bug certainly looks related. :)

The code change added an if (tag.loaded) check. Perhaps there is a race condition on browser startup where the plugins haven't been loaded yet?

https://hg.mozilla.org/mozilla-central/rev/225c129a3f3e

Since the regressing code change is specific to plugins, and given that Firefox will drop Flash support in Fx84 (October Nightly), I don't think anyone should invest any more time debugging or fixing this bug. But I'll leave the decision to WONTFIX this bug or not to you all.

Comment 10

[Release mgmt bot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:mixedpuppy, could you have a look please?

For more information, please visit auto_nag documentation.

Comment 11

[opi123]

Adobe Flash is no longer supported.