[tor-bugs] #24423 [Core Tor/Tor]: Fix STACK warnings in Tor

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#24423: Fix STACK warnings in Tor
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 Reporter:  nickm         |          Owner:  nickm
     Type:  defect        |         Status:  assigned
 Priority:  Medium        |      Milestone:  Tor: 0.3.2.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:                |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:
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Comment (by nickm):

 I have fixes in my branch `stack_fixes_032`, with each issue getting a
 separate commit.  I have not re-run this branch under STACK.

 There seem to be two kinds of issues here:
   1) We checked to see whether something that can't possibly be negative
 is negative.  Sometimes this means that we had done the arithmetic wrong;
 sometimes it means that the check was erroneous.
   2) We check for NULL-ness of a pointer that can't possibly be NULL.
 This usually means that the NULL check was redundant.

 I'd like a second opinion on all the arithmetic fixes, especially to know
 if you think they represent a real bug that needs a separate ticket.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24423#comment:1>
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