[tor-bugs] #6386 [Firefox Patch Issues]: Deadlock/hang on TBB New Identity

Tor Bug Tracker & Wiki blackhole at torproject.org
Sat Mar 2 00:19:04 UTC 2013


#6386: Deadlock/hang on TBB New Identity
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 Reporter:  mikeperry             |          Owner:  mikeperry
     Type:  defect                |         Status:  new      
 Priority:  major                 |      Milestone:           
Component:  Firefox Patch Issues  |        Version:           
 Keywords:                        |         Parent:           
   Points:                        |   Actualpoints:           
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Comment(by mikeperry):

 Aha: I found https://hg.mozilla.org/mozilla-central/rev/38fcd9047d39 while
 digging through the cache service code. Apparently, it was added to the
 cache shutdown syncing code because of a crash bug:
 https://bugzilla.mozilla.org/show_bug.cgi?id=673543. However, looking at
 the codepaths, the fix for that crash would *also* prevent the release of
 our patch condition's lock by nsCacheService::ProcessRequest(). That code
 releases the lock we were holding and then waits for *another* condition
 using the same lock. This could definitely cause our condition to never
 get properly signaled if the timing was just right, causing deadlock.

 So it's possible that their crash fix will fix this issue too. I'm going
 to apply it to our #5715 patch and I guess we'll just wait another couple
 months to see if this race resurfaces, at which point I suppose I could
 dig deeper into #7637. But at a glance, #7637 will require way more
 mechanics than this simple fix, and it might re-introduce the evercookie
 race. So here's hoping this is it!

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6386#comment:6>
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