[ruby-core:116408] [Ruby master Bug#20207] Segmentation fault for a regexp containing positive and negative lookaheads

["byroot (Jean Boussier) via ruby-core" <ruby-core@ml.ruby-lang.org>]

Issue #20207 has been updated by byroot (Jean Boussier).


@nobu I do get a SEGV on both x86_64 and ARM64:

```
-- C level backtrace information -------------------------------------------
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(rb_vm_bugreport+0xb4c) [0x100fd6534]
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(rb_bug_for_fatal_signal+0x100) [0x100e197c8]
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(sig_do_nothing+0x0) [0x100f3e14c]
/usr/lib/system/libsystem_platform.dylib(_sigtramp+0x38) [0x18494da24]
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(match_at+0x21dc) [0x100f1d744]
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(onig_search_gpos+0x694) [0x100f25b04]
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(rb_reg_match_p+0x1cc) [0x100f09448]
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(vm_call_cfunc_with_frame_+0xf0) [0x100fc9228]
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(vm_exec_core+0x2048) [0x100faef80]
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(rb_vm_exec+0x1ec) [0x100fabdc4]
/opt/rubies/3.3.0/lib/libruby.3.3.dylib(rb_f_eval+0x1d8) [0x100fbaf7c]
```

----------------------------------------
Bug #20207: Segmentation fault for a regexp containing positive and negative lookaheads
https://bugs.ruby-lang.org/issues/20207#change-106430

* Author: Sundeep (Sundeep Agarwal)
* Status: Open
* Priority: Normal
* Assignee: make_now_just (Hiroya Fujinami)
* Backport: 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONTNEED, 3.3: REQUIRED
----------------------------------------
I'm getting segmentation fault for the following regexp with Ruby 3.3.0:

``` ruby
puts 'clan'.match?(/(?=.*a)(?!.*n)/)
```

This is the minimal example for which I was able to produce the issue. `a` and `n` in the above example
are just a sample, can be other character combinations too. There has to be at least two characters
before them in the input string (`cl` in the above example).

The error is seen when the above code is run from a file, but only occasionally from irb.
When run from a file, most of the time I get segmentation fault (see attached log file),
but sometimes I get the following error:

``` ruby
lookaround.rb:1:in `match?': undefined bytecode (bug): /(?=.*a)(?!.*n)/ (RegexpError)
	from lookaround.rb:1:in `<main>'
```

When asked in the r/ruby forum, somebody else was able to reproduce this issue.
They also mentioned that the issue wasn't seen in the Ruby 3.2.2 version.

---Files--------------------------------
lookaround_segfault.log (15.9 KB)


-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/