2001149 - We don't add user font sandbox rules for the profile picker gpu process

Status: RESOLVED FIXED

(Core :: Security: Process Sandboxing, defect, P1)

Description

[Bob Owen (:bobowen)]

Analysis of the get_first_matching_font crashes from bug 1967071 revealed that they all had a GraphicsCriticalError containing "Shader disk cache is not supported".
We add rules to give access to this normally, but not in the profile picker, because GeckoDependentInitialize (where we cache the profile dir) is not called.
Currently, we also use the gecko directory service to cache the user's AppData\Local dir, so we don't add user font rules for the picker process either.

Looking at some of the dumps for these crashes, they all have various Segoe UI font file paths from the windows user's font dir in their stacks.
(Some with slightly odd names: i.e. with _0 or _1 appended as if they've been copied.)
This is odd because these should be in the system font dir as protected fonts.
It's not easy to override that, because only TrustedInstaller has full access to that dir and these are protected system fonts and a standard attempt to uninstall using the system font dialog gets blocked. I'm sure it is possible though.

We can easily get the AppData\Local dir from windows directly like we do for other dirs, so we can always add these rules.

Comment 1

[Bob Owen (:bobowen)]

Attachment: Bug 2001149 - Get the user's AppData\Local dir directly from windows for sandbox rules. r=handyman!

This means we can add user font rules for the profile picker gpu process.

Comment 2

[Bob Owen (:bobowen)]

https://treeherder.mozilla.org/jobs?repo=try&revision=acad1e84659abf3e3a8bdf98d549853506ff97a6

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/eefa6b4a5a06
https://hg.mozilla.org/integration/autoland/rev/62c6b48904d4
Get the user's AppData\Local dir directly from windows for sandbox rules. r=handyman

Comment 4

[amarc]

https://hg.mozilla.org/mozilla-central/rev/62c6b48904d4

Comment 5

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

The patch landed in nightly and beta is affected.
:bobowen, 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-firefox146 to wontfix.

For more information, please visit BugBot documentation.

Comment 6

[Bob Owen (:bobowen)]

This is only on early Beta.