From: nobu@...
Date: 2017-04-14T13:05:56+00:00
Subject: [ruby-core:80687] [Ruby trunk Bug#13164][Open] A second `SystemStackError` exception results in `Segmentation fault (core dumped)`

Issue #13164 has been updated by nobu (Nobuyoshi Nakada).

Status changed from Closed to Open

On Linux, fixed by unblocking the received signal.
But it has no effect on mac OS and seems to need `--with-setjmp-type=setjmp`.


----------------------------------------
Bug #13164: A second `SystemStackError` exception  results in `Segmentation fault (core dumped)`
https://bugs.ruby-lang.org/issues/13164#change-64232

* Author: myst (Boaz Segev)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.4.0p0 (2016-12-24 revision 57164) [x86_64-darwin16]
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
----------------------------------------
This issue is was exposed by leveraging the fact that `Object#hash` is implemented recursively for core Ruby datatypes (i.e., Hash and Array). See the discussion here: https://github.com/boazsegev/combine_pdf/pull/91#issuecomment-275552131.

TO reproduce the issue, explode the stack **twice**.

Expected results: 

SystemStackError will be raised both times.

Actual results:

SystemStackError is raised once. The second time will cause a core dump.

Code to cause core dump:

~~~ ruby
def compute_nest_depth
  h = {nest: {}}
  nest = h[:nest]
  i = 0

  while true
    i += 1
    puts "nested #{i}" if ((i & 511) == 0)
    next_nest = { nest: {} }
    nest[:nest] = next_nest
    nest = next_nest[:nest]
    h.hash
  end

rescue SystemStackError
  puts "Stack exploded at nesting #{i}"
end

counter = 0;
while(true)
  begin
    counter +=1
    puts "starting test #{counter}"
    compute_nest_depth
  rescue SystemStackError => e
    nil
  ensure
    puts "test #{counter} complete"
  end
end

~~~

results:

~~~
starting test 1
nested 512
nested 1024
nested 1536
nested 2048
nested 2560
Stack exploded at nesting 2783
test 1 complete
starting test 2
nested 512
nested 1024
nested 1536
nested 2048
nested 2560
Segmentation fault (core dumped)
~~~



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