[ruby-core:115601] [Ruby master Bug#20042] ObjectSpace finalizer can cause segfault

6 Dec 2023

      Issue #20042 has been updated by byroot (Jean Boussier).

Actually nevermind, my simplification was wrong. Using exactly your script, it crash all the way to 3.0.

```
:x: 3.0
｀｀｀<internal:gc>:35: [BUG] Stack consistency error (sp: 17, bp: 15)
ruby 3.0.5p211 (2022-11-24 revision ba5cf0f7c5) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0003 p:0011 s:0017 e:000014 METHOD <internal:gc>:35
c:0002 p:0060 s:0007 E:001af8 EVAL   -:10 [FINISH]
c:0001 p:0000 s:0003 E:002140 (none) [FINISH]
-- Ruby level backtrace information ----------------------------------------

:x: 3.1
<internal:gc>:34: warning: Exception in finalizer #<Finalizer:0x00007fc730f72e30>
-:2:in `call': wrong number of arguments (given 1, expected 0) (ArgumentError)
    from <internal:gc>:34:in `start'
    from -:10:in `<main>'
<internal:gc>:35:in `start': Stack consistency error (sp: 17, bp: 15) (fatal)

:x: 3.2
｀｀｀<internal:gc>:34: warning: Exception in finalizer #<Finalizer:0x00007fe950ab9d98>
-:2:in `call': wrong number of arguments (given 1, expected 0) (ArgumentError)
    from <internal:gc>:34:in `start'
    from -:10:in `<main>'
<internal:gc>:35: [BUG] Stack consistency error (sp: 17, bp: 15)

:x: 7e05e9ff94 (2023-12-06T06:48:55Z)
｀｀｀<internal:gc>:39: warning: Exception in finalizer #<Finalizer:0x00007fae4e314850>
-:2:in `call': wrong number of arguments (given 1, expected 0) (ArgumentError)
    from <internal:gc>:39:in `start'
    from -:10:in `<main>'
<internal:gc>:40: [BUG] Stack consistency error (sp: 17, bp: 15)

```

----------------------------------------
Bug #20042: ObjectSpace finalizer can cause segfault
https://bugs.ruby-lang.org/issues/20042#change-105531

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
* Backport: 3.0: DONTNEED, 3.1: REQUIRED, 3.2: REQUIRED
----------------------------------------
```ruby
class Finalizer
  def call # <- missing (id) argument
  end
end

object = Object.new
ObjectSpace.define_finalizer(object, Finalizer.new)
object = nil

GC.start # segfaults here
```

-- 
https://bugs.ruby-lang.org/