[tor-bugs] #15901 [Tor]: apparent memory corruption -- very difficult to isolate

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#15901: apparent memory corruption -- very difficult to isolate
---------------------------+--------------------------------
     Reporter:  starlight  |      Owner:
         Type:  defect     |     Status:  new
     Priority:  critical   |  Milestone:  Tor: 0.2.7.x-final
    Component:  Tor        |    Version:  Tor: 0.2.5.12
   Resolution:             |   Keywords:
Actual Points:             |  Parent ID:
       Points:             |
---------------------------+--------------------------------

Comment (by starlight):

 That was a case of false correlation rather than
 causation.  Control channel has nothing to do
 with it.  Read recent updates here rather
 than the initial report.

 At this point I believe the problem is a
 race-condition bug in OpenSSL that is exposed
 by compiling and linking OpenSSL libraries
 with LTO.

 Now running for awhile with non-LTO OpenSSL
 and with `NumCPUs 1` and so far no corruption
 events.  However this does not prove anything
 and at some point I may go back and run
 TSAN and try and shake out the bug.

 NOTE:  `NumCPUs 1` does not eliminate threading,
 what it does is make the crypto-worker pool
 have one thread.  The bug could be either
 two crypto-workers colliding or a crypto-
 worker colliding with the main thread.
 Perhaps TSAN will show which.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/15901#comment:18>
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