1978217 - Inline stylesheet caching is not aware of background-image relative URLs

Status: VERIFIED FIXED

(Core :: CSS Parsing and Computation, defect, P3)

Description

[Alicia Boya]

Attachment: Minimal repro

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0

Steps to reproduce:

I produced two HTMLs in different directories with the same inline stylesheet referencing an image with the same relative URL.

The relative URL only pointed to an existing file in one of the directories.

Actual results:

When navigating from the first document to the second, the image from the first document still showed, even though it should have been a 404 in the second document.

Expected results:

The image should not have loaded.

Furthermore, I have made a minimal repro where instead of a 404, both directories have an image with the same name. Firefox still pulls whichever image was loaded first during navigation.

The issue does not reproduce on file:/// URIs. To use the repro, serve it in localhost, navigate to index.html and click the link. If the image has the same color on navigation, the image is wrongly cached.

Comment 1

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

The Bugbug bot thinks this bug should belong to the 'Core::DOM: Navigation' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

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

Set release status flags based on info from the regressing bug 1956486

:emilio, since you are the author of the regressor, bug 1956486, could you take a look?

For more information, please visit BugBot documentation.

Comment 3

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

Set release status flags based on info from the regressing bug 1956486

Comment 5

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1978217 - Record use counter data inline in StylesheetContents. r=#style,#layout

No behavior change, but this is simpler. I want to reuse the use
counters mechanism to fix this bug because it's a very trivial way of
asking questions about the parsed data and we need to plumb it through
the same places.

Comment 6

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1978217 - Add support for custom style use counters. r=#style,#layout

In the future if we need to we can hook these up to telemetry (in fact it's not
hard, we just need to do that in Document::ReportUseCounters).

For now I want to start using them to record whether we might have a data URI.

Comment 7

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1978217 - Don't share sheets using relative URIs when it's not safe to do so. r=#style,#layout

Track whether an inline sheet might have uris that depend on the base, and
avoid caching them if appropriate.

Comment 8

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1978217 - Add a test for relative URIs inside cacheable inline stylesheets. r=#style,#layout

This tests both @import and regular declarations. Without this fix, the test
page renders blue, rather than a blue background with a purple square inside
and a smaller lime square inside.

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/513bfd909713
https://hg.mozilla.org/integration/autoland/rev/a91bf9bf3237
Record use counter data inline in StylesheetContents. r=firefox-style-system-reviewers,layout-reviewers,dshin
https://github.com/mozilla-firefox/firefox/commit/8b5ee7f9aa8a
https://hg.mozilla.org/integration/autoland/rev/fd51678da995
Add support for custom style use counters. r=firefox-style-system-reviewers,layout-reviewers,dshin
https://github.com/mozilla-firefox/firefox/commit/493d0f23cb3d
https://hg.mozilla.org/integration/autoland/rev/76a354cd17e5
Don't share sheets using relative URIs when it's not safe to do so. r=firefox-style-system-reviewers,layout-reviewers,dshin
https://github.com/mozilla-firefox/firefox/commit/f96a8e0cddb2
https://hg.mozilla.org/integration/autoland/rev/dc1a3742906a
Add a test for relative URIs inside cacheable inline stylesheets. r=firefox-style-system-reviewers,layout-reviewers,dshin
https://github.com/mozilla-firefox/firefox/commit/e3dc6c04527e
https://hg.mozilla.org/integration/autoland/rev/65febe193cb0
apply code formatting via Lando

Comment 10

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

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/53913 for changes under testing/web-platform/tests

Comment 11

[Alice0775 White]

[Tracking Requested - why for this release]: The page style sheet sometimes would not load.

Comment 12

[pstanciu]

https://hg.mozilla.org/mozilla-central/rev/a91bf9bf3237
https://hg.mozilla.org/mozilla-central/rev/fd51678da995
https://hg.mozilla.org/mozilla-central/rev/76a354cd17e5
https://hg.mozilla.org/mozilla-central/rev/dc1a3742906a
https://hg.mozilla.org/mozilla-central/rev/65febe193cb0

Comment 13

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

Upstream PR merged by moz-wptsync-bot

Comment 14

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

Upstream PR merged by moz-wptsync-bot

Comment 15

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

The patch landed in nightly and beta is affected.
:emilio, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
  • See https://wiki.mozilla.org/Release_Management/Requesting_an_Uplift for documentation on how to request an uplift.
• If no, please set status-firefox142 to wontfix.

For more information, please visit BugBot documentation.

Comment 16

[Emilio Cobos Álvarez [:emilio]]

Comment on attachment 9502234 [details]
Bug 1978217 - Record use counter data inline in StylesheetContents. r=#style,#layout

Beta/Release Uplift Approval Request

• User impact if declined/Reason for urgency: Fixes correctness issue that breaks some sites in the wild, see bug 1978555
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: comment 0, bug 1978555
• List of other uplifts needed: none
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): While the changeset is big, it's not particularly complex, and it reuses well-tested infrastructure for CSS use counters.
• String changes made/needed: none
• Is Android affected?: Yes

ESR Uplift Approval Request

• If this is not a sec:{high,crit} bug, please state case for ESR consideration: see above
• User impact if declined: see above
• Fix Landed on Version: 143
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): See above. An alternative would be to disable the caching in this "different base URI" situation, but that's a bit unfortunate because the regressing bug did bring performance and memory usage improvements.

Comment 17

[Dianna Smith [:diannaS]]

Comment on attachment 9502234 [details]
Bug 1978217 - Record use counter data inline in StylesheetContents. r=#style,#layout

Approved for 142.0b3

Comment 18

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/44a16b4ee3be
https://hg.mozilla.org/releases/mozilla-beta/rev/046cd4ca91c4
https://github.com/mozilla-firefox/firefox/commit/5f8f00c104fd
https://hg.mozilla.org/releases/mozilla-beta/rev/705ed6488546
https://github.com/mozilla-firefox/firefox/commit/0fd973e948f6
https://hg.mozilla.org/releases/mozilla-beta/rev/41d3d62355df
https://github.com/mozilla-firefox/firefox/commit/70ef3ad29c97
https://hg.mozilla.org/releases/mozilla-beta/rev/642305b9c557
https://github.com/mozilla-firefox/firefox/commit/f7c35bc7fbeb
https://hg.mozilla.org/releases/mozilla-beta/rev/ef553cb4508b

Comment 19

[Ciprian Georgiu, Desktop QA]

I've reproduced this issue with steps from comment 0 and the ones from bug 1978555 using an affected Nightly build (2025-07-19).

The issue is verified as fixed on Beta 142.0b3 (treeherder build) and latest Nightly 143.0a1 under Win 11, macOS 15 and Ubuntu 24.

Comment 20

[Dianna Smith [:diannaS]]

Comment on attachment 9502234 [details]
Bug 1978217 - Record use counter data inline in StylesheetContents. r=#style,#layout

Approved for 140.2.0esr

Comment 21

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-esr140/rev/9f7c116b6313
https://hg.mozilla.org/releases/mozilla-esr140/rev/b5c68cf8f03d
https://hg.mozilla.org/releases/mozilla-esr140/rev/a5a274b629d8
https://hg.mozilla.org/releases/mozilla-esr140/rev/55c7c76cff41
https://hg.mozilla.org/releases/mozilla-esr140/rev/30255082489e

Comment 23

[Ciprian Georgiu, Desktop QA]

This issue is also verified as fixed on Esr 140.2.0 (treeherder build) using Win 11, macOS 15 and Ubuntu 24.04.