[tor-bugs] #8770 [Firefox Patch Issues]: Verify that @font-face fallback fonts can't be probed

Thu Apr 25 00:02:14 UTC 2013

#8770: Verify that @font-face fallback fonts can't be probed
----------------------------------+-----------------------------------------
 Reporter:  mikeperry             |          Owner:  mikeperry
     Type:  task                  |         Status:  new      
 Priority:  major                 |      Milestone:           
Component:  Firefox Patch Issues  |        Version:           
 Keywords:  tbb-fingerprinting    |         Parent:           
   Points:                        |   Actualpoints:           
----------------------------------+-----------------------------------------
 In #8455, I disabled the local fallback rendering for @font-face. I did
 not attempt to disable all of the code that handles cases where WebFonts
 weren't downloaded yet, because I was hesitant to introduce bugs,
 especially without a test case to verify that what I disabled was actually
 relevant to font probing.

 However, there did appear to be sections of the code that at least
 internally allowed Firefox to estimate font sizes *before* the webfont
 completed loading. It was not immediately clear to me if these estimations
 were available to content or not, and which fonts they were based on.

 If they are available, it would be very useful to have a test case to
 verify against as I try removing/altering some of those codepaths.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/8770>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online