[tor-bugs] #24806 [Core Tor/Tor]: LTS branch leaks memory continuously under stress/attack, requires back-port of 0.3.2.8-rc fixes to remain viable

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#24806: LTS branch leaks memory continuously under stress/attack, requires back-
port of 0.3.2.8-rc fixes to remain viable
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 Reporter:  starlight     |          Owner:  (none)
     Type:  defect        |         Status:  new
 Priority:  Medium        |      Milestone:
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:                |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:
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Comment (by starlight):

 The event had characteristics of a leak.  I was watching on-and-off due to
 cycles of earlier memory exhaustion events followed by corrective tuning,
 along with current huge volumes of excess egress flow that matches the
 description of HSDIR query traffic.  Tor daemon total memory gradually
 climbed for hours from 1.5GB.  Saw it at 2.2GB; two hours later came back
 and observed the final footprint hit 2.4GB.

 Egress traffic was continuously near saturation, limited by CPU rather
 than bandwidth and it's conceivable a pile-up of allocations consumed the
 memory.  However CPU backed substantially off of 100% at times.

 Earlier while working on attack mitigation, I observed in debug logging
 the attacker creates large numbers of circuits, destroys them all-at-once;
 repeats the cycle endlessly.

 Hard to say for certain.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24806#comment:3>
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