From: "kosaki (Motohiro KOSAKI)" <kosaki.motohiro@...>
Date: 2012-11-09T01:31:27+09:00
Subject: [ruby-core:49113] [ruby-trunk - Bug #7009] Crash in method_missing


Issue #7009 has been updated by kosaki (Motohiro KOSAKI).

Category set to core
Assignee changed from kosaki (Motohiro KOSAKI) to nobu (Nobuyoshi Nakada)
Target version changed from 2.0.0 to 1.9.3

This issue works on trunk.

% ./ruby-trunk ../test.rb
../test.rb:3: stack level too deep (SystemStackError)

Recently nobu changed stack overflow detection logic, I suspect it also fixes this issue.
Nobu, if yes, can you please tell us exact commit number what revision should be backported.



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Bug #7009: Crash in method_missing
https://bugs.ruby-lang.org/issues/7009#change-32644

Author: alexcoplan (Alex Coplan)
Status: Assigned
Priority: Low
Assignee: nobu (Nobuyoshi Nakada)
Category: core
Target version: 1.9.3
ruby -v: ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin11.4.0]


=begin
Given the following code:

 def method_missing(sym, *args)
   foo(sym, *args)
 end

 bar

When (({bar})) is called, it triggers method_missing (because bar is undefined). Inside method_missing, it calls (({foo})) (another undefined method), and that in turn calls method_missing, but this time the method name and the rest of the arguments are passed back to method missing. This results in an ever-increasing number of arguments. If I add a debug line like so:

 def method_missing(sym, *args)
   print "#{sym} #{args}\n"
   foo(sym, *args)
 end

 bar # undefined method

then this is the first few lines of output:

 bar []
 foo [:bar]
 foo [:foo, :bar]
 foo [:foo, :foo, :bar]
 foo [:foo, :foo, :foo, :bar]

The expected result is that it should report a SystemStackError

 mm.rb:2: stack level too deep (SystemStackError)

The actual result is this:

 mm.rb:2: [BUG] Segmentation fault
 ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin11.4.0]
 
 -- Control frame information -----------------------------------------------
 c:2695 p:0037 s:10775 b:9428 l:009427 d:009427 METHOD thing.rb:3
 c:2694 p:---- s:9423 b:9423 l:009422 d:009422 FINISH
 c:2693 p:0037 s:9421 b:9421 l:009420 d:009420 METHOD thing.rb:3
 c:2692 p:---- s:9416 b:9416 l:009415 d:009415 FINISH

That crash log goes on a lot longer and I will attach both the ruby crash log and the system crash log.


-- 
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