[ruby-core:120362] [Ruby master Bug#20950] Use-after-free in ep in Proc#dup for ifunc procs

Issue #20950 has been updated by nagachika (Tomoyuki Chikanaga).


Backporting only 92dd9734a967c20e628c8f77c5ce700058dcd58c into ruby_3_2 causes a VM_ASSERT() failure in vm_ep_in_heap_p_().
I believe there are additional changesets that should be backported beforehand.
Any suggestions would be greatly appreciated.

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Bug #20950: Use-after-free in ep in Proc#dup for ifunc procs
https://bugs.ruby-lang.org/issues/20950#change-111140

* Author: peterzhu2118 (Peter Zhu)
* Status: Closed
* Backport: 3.1: WONTFIX, 3.2: REQUIRED, 3.3: REQUIRED
----------------------------------------
GitHub PR: https://github.com/ruby/ruby/pull/12319

ifunc proc has the ep allocated in the data of the TypedData object. If an ifunc proc is duplicated, the ep points to the ep of the source object. If the source object is freed, then the ep of the duplicated object now points to a freed memory region. If we try to use the ep we could crash.

For example, the following script crashes:

```ruby
p = { a: 1 }.to_proc
100.times do
  p = p.dup
  GC.start
  p.call
rescue ArgumentError
end
```

This commit changes ifunc proc to also duplicate the ep when it is duplicated.



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