[tor-bugs] #23104 [Applications/Tor Browser]: CSS line-height reveals the platform Tor Browser is running on

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#23104: CSS line-height reveals the platform Tor Browser is running on
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 Reporter:  gk                        |          Owner:  igt0
     Type:  defect                    |         Status:  needs_revision
 Priority:  Medium                    |      Milestone:
Component:  Applications/Tor Browser  |        Version:
 Severity:  Normal                    |     Resolution:
 Keywords:  tbb-fingerprinting-os     |  Actual Points:
Parent ID:                            |         Points:
 Reviewer:  gk                        |        Sponsor:
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Changes (by gk):

 * status:  needs_review => needs_revision
 * keywords:  tbb-fingerprinting-os, TorBrowserTeam201709R => tbb-
     fingerprinting-os


Comment:

 Okay, some comments. I just tested Windows and Linux builds and it seems
 your fix works for me. Nice! Do you have a test which let you check your
 patch works correctly? If not, how have you verified your patch does
 indeed fix the problem?

 In Tor Browser (and Mozilla in Firefox) we bind our fingerprinting
 resistance to the `privacy.resistFingerprinting` preference: only when
 that preference is set to `true` all the fingerprinting patches are
 active. If not then the default Firefox behavior in that regard is
 visible. That way it is much more easier for Mozilla to upstream our
 patches.

 Could you make sure as well that your code is only active when this
 preference is set to `true` and inactive otherwise? Bonus points for a
 unit test showing that your patch does indeed do what it claims it does.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23104#comment:7>
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