[Webkit-unassigned] [Bug 235475] New: Loading gets stuck after back-navigation involving COOP header

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=235475

            Bug ID: 235475
           Summary: Loading gets stuck after back-navigation involving
                    COOP header
           Product: WebKit
           Version: Safari 15
          Hardware: iPhone / iPad
                OS: iOS 15
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: New Bugs
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: remi at brave.com

Overview
========

Back-navigation gets stuck in infinite loading under some circumstances when the Cross-Origin-Opener-Policy header is in use.
This bug seems to impact only iOS and iPadOS 15.2, using any browser (e.g. we tried on Safari, Brave and Firefox).
It seems like the COOP header was not supported before this version (https://webkit.org/blog/12140/new-webkit-features-in-safari-15-2/)

Steps to reproduce
==================

Here is a page which allows to reproduce the issue: https://fmarier.org/coop-safari/link.html (Thank you Francois)
The flow is the following:
- 'Site 1' sets the COOP header (either with value 'same-origin-allow-popups' or 'same-origin')
- User navigates to 'site 2' from 'site 1' (e.g. in this case Instagram, which is how we discovered the issue in the first place)
- User navigates backward from 'site 2' to 'site 1', but the loading gets stuck.

Expected result
===============

It should be possible to navigate backward from 'site 2' to 'site 1' without the browser getting stuck loading.

Additional information
======================

Removing the COOP header from 'site 1' results in back-navigation working as expected.

Speculation
===========

It is not 100% clear what is causing this issue, but it seems to happen in some cases when 'site 1' and 'site 2' both define a COOP header, and user tries to navigation back from 'site 2' to 'site 1'.

Build Date & Hardware
=====================

The version of iOS where the issue was observed is 15.2.1 (19C63), the same issue appears on iPadOS 15.2 as well. We could not reproduce on the previous iOS version nor on the desktop version of Safari.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20220122/ecc4f193/attachment.htm>