Bug #21180: SEGV while marking `imemo_env->iseq`

• Status: Closed
• Assignee: -
• Target version: -
• Backport: 3.1: DONTNEED, 3.2: DONE, 3.3: DONE, 3.4: DONE

[alanwu (Alan Wu)]

This issue happens most realistically for people using a fiber scheduler (through e.g. the async gem), on Ruby 3.4.x and on Linux, but the following crashes for me for 3.2 and newer on macOS:

$ tail -n +1 test.rb ret1.rb
==> test.rb <==
require 'continuation'
module Warning
  def self.warn(message)
    GC.stress = true
    callcc
  end
end
require_relative 'ret1'

==> ret1.rb <==
return 1

Keywords for people searching: rb_imemo_mark_and_move, Note that the Fiber scheduler is enabled.

Working on a fix at https://github.com/ruby/ruby/pull/12898

[alanwu (Alan Wu)]

• Description updated (diff)

[alanwu (Alan Wu)]

• Description updated (diff)

[alanwu (Alan Wu)]

• Status changed from Open to Closed

Applied in changeset git|08b3a45bc97c835b4677bf76dbce68fd51d81897.

---

Push a real iseq in rb_vm_push_frame_fname()

Previously, vm_make_env_each() (used during proc
creation and for the debug inspector C API) picked up the
non-GC-allocated iseq that rb_vm_push_frame_fname() creates,
which led to a SEGV when the GC tried to mark the non GC object.

Put a real iseq imemo instead. Speed should be about the same since
the old code also did a imemo allocation and a malloc allocation.

Real iseq allows ironing out the special-casing of dummy frames in
rb_execution_context_mark() and rb_execution_context_update(). A check
is added to RubyVM::ISeq#eval, though, to stop attempts to run dummy
iseqs.

[Bug #21180]

Co-authored-by: Aaron Patterson [e-mail]

[hsbt (Hiroshi SHIBATA)]

• Backport changed from 3.1: DONTNEED, 3.2: REQUIRED, 3.3: REQUIRED, 3.4: REQUIRED to 3.1: DONTNEED, 3.2: DONE, 3.3: REQUIRED, 3.4: REQUIRED

ruby_3_2 commit:e325f5b1636d7eb59a9cc2f35ba6d91d6da4f459 merged revision(s) 08b3a45bc97c835b4677bf76dbce68fd51d81897.

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 3.1: DONTNEED, 3.2: DONE, 3.3: REQUIRED, 3.4: REQUIRED to 3.1: DONTNEED, 3.2: DONE, 3.3: DONE, 3.4: REQUIRED

ruby_3_3 2b2ab1a67c236eb0c47e63e8adcf877b0d20a38c merged revision(s) 08b3a45bc97c835b4677bf76dbce68fd51d81897.

[maximecb (Maxime Chevalier-Boisvert)]

• Backport changed from 3.1: DONTNEED, 3.2: DONE, 3.3: DONE, 3.4: REQUIRED to 3.1: DONTNEED, 3.2: DONE, 3.3: DONE, 3.4: DONE