From: "nagachika (Tomoyuki Chikanaga)" <noreply@...>
Date: 2022-09-25T04:43:56+00:00
Subject: [ruby-core:110058] [Ruby master Bug#18902] Thread#value crash if the thread was killed because of a fork

Issue #18902 has been updated by nagachika (Tomoyuki Chikanaga).

Backport changed from 2.7: REQUIRED, 3.0: REQUIRED, 3.1: REQUIRED to 2.7: REQUIRED, 3.0: REQUIRED, 3.1: DONE

ruby_3_1 720de2008ca06edb22e5ad7d1432fee4f2575e00 merged revision(s) 65ae2bb2e045aa8b668d3c30515f5a6cb3eb68ad.

----------------------------------------
Bug #18902: Thread#value crash if the thread was killed because of a fork
https://bugs.ruby-lang.org/issues/18902#change-99309

* Author: byroot (Jean Boussier)
* Status: Closed
* Priority: Normal
* ruby -v: ruby 3.2.0dev, ruby 3.1.2p20, ruby 3.0.3p157, ruby 2.7.5p203 
* Backport: 2.7: REQUIRED, 3.0: REQUIRED, 3.1: DONE
----------------------------------------
Reproduction script 

```ruby
thr = Thread.new { sleep 10} 
fork do
  p thr.status # =>false
  p thr.join # => #<Thread:0x00000001008ae480 /tmp/thread-join.rb:1 dead>
  p thr.value # Assertion Failed: ./vm_core.h:1303:VM_ENV_FLAGS:FIXNUM_P(flags) (or crash if RUBY_DEBUG isn't set)
end
```

What happens is that `rb_thread_t->value` is initialized to `Qundef`, so when the thread is killed by a fork, `Thread#value` tries to return `Qundef` which laters crash the VM.

I have a patch incomming.




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

Unsubscribe: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>