[tor-bugs] #29527 [Core Tor/Tor]: Division by zero: undefined behaviour in circuitpadding/circuitpadding_sample_distribution test

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#29527: Division by zero: undefined behaviour in
circuitpadding/circuitpadding_sample_distribution test
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  (none)
     Type:  defect                               |         Status:
                                                 |  needs_review
 Priority:  High                                 |      Milestone:  Tor:
                                                 |  0.4.0.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  regression, tor-ci, tor-test,        |  Actual Points:
  040-must                                       |
Parent ID:                                       |         Points:
 Reviewer:  mikeperry                            |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by riastradh):

 Replying to [comment:11 asn]:
 > The first commit (a64ccf151f) fixes the probability distribution
 parameters that Riastradh mentioned with bold in comment:7. The second
 commit (f708055e9f) silences float-divide-by-zero as suggested by #29528.

 Cool.  One suggestion for a change and one comment:

 - It might be helpful if you put a comment on each line describing what
 the name and purpose of the parameter is, like `k, shape parameter`,
 because I can never remember which one goes first and which one goes last.

 - This is the kind of code where the `struct weibull dist = {
 WEIBULL(dist), k = ..., lambda = ...}` can be much more legible than
 `struct circpad_distribution dist = { .type = CIRCPAD_DIST_WEIBULL,
 .param1 = ..., .param2 = ... }`.  (Obviously changing the code to work
 like that here is more involved than would be warranted, even if you
 wanted it, for this particular issue, of course.)

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29527#comment:13>
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