Bug 299742 – [css-anchor-position-1] Style resolution repeats indefinitely when position-try box is in a display: none tree

• Status: RESOLVED
• Resolution: FIXED
• Component: CSS

Created attachment 476893 [details]
Minimal Case to trigger the popover crash

When using `position-try-fallbacks` on a popover element if the container of the popover is to become hidden via `display: none` (even if the popover is not currently visible) the browser tab will hang, and cause a spike in CPU usage. On iOS this causes the device to become hot if the tab is left open.

Note if the popover container's initial state is set to `display: none`  then there is no issue. It only happens if the container later becomes `display: none`.

Minimal reproduction case is attached

This affects existing websites, that have been using popovers with fallbacks before Safari 26.

[Alexey Proskuryakov]

Thank you for the report, I can reproduce. Looks like updateStyleIfNeeded() is calling Style::TreeResolver::resolve() in a tight loop.

[Radar WebKit Bug Importer]

<rdar://problem/161570947>

[Kiet Ho]

Perhaps dupe of bug 301310

[Kiet Ho]

Pull request: https://github.com/WebKit/WebKit/pull/52953

[EWS]

Committed 302254@main (2826fcdebc5b): <https://commits.webkit.org/302254@main>

Reviewed commits have been landed. Closing PR #52953 and removing active labels.

[Kiet Ho]

Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/55738

[Daniel J]

Still broken in Safari 26.1 (Mac OS) - has this been released?