1984635 - Rendering 4th recursive iframe (here in ABABA case) broken

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Manuel Bucher [:manuel]]

Attachment: bad-good.webm

Url: https://sah.yet.cx/storage-access/?iframe=wiki,cx,wiki,cx
Regression bug found with moz-regression

Haven't seen other cases, but there might be a simpler ones.

STR:

1. open https://sah.yet.cx/storage-access/?iframe=wiki,cx,wiki,cx
2. scroll down

Comment 1

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

Set release status flags based on info from the regressing bug 1891335

:emilio, since you are the author of the regressor, bug 1891335, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 2

[Emilio Cobos Álvarez [:emilio]]

I think this is a pre-existing IntersectionObserver bug with OOP iframes if the iframe is very tall.

Comment 3

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1984635 - Fix IntersectionObserver implicit root behavior on OOP iframes. r=#layout

aRootBounds is meaningless in that case, since it's the top level
viewport bounds, not the iframe's viewport bounds (which might be a lot
taller).

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/0123e6230150
https://hg.mozilla.org/integration/autoland/rev/86b37d216aeb
Fix IntersectionObserver implicit root behavior on OOP iframes. r=layout-reviewers,dshin

Comment 5

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/54528 for changes under testing/web-platform/tests

Comment 6

[Cristina Horotan [:chorotan]]

https://hg.mozilla.org/mozilla-central/rev/86b37d216aeb

Comment 7

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot

Comment 8

[Ryan VanderMeulen [:RyanVM]]

Did you want to nominate this for uplift? Go ahead and do so if yes.

Comment 9

[Emilio Cobos Álvarez [:emilio]]

Unless we know of sites affected by this I think this can ride the trains.