From: "byroot (Jean Boussier) via ruby-core" <ruby-core@...>
Date: 2024-01-24T12:13:05+00:00
Subject: [ruby-core:116409] [Ruby master Bug#20207] Segmentation fault for a regexp containing positive and negative lookaheads

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


Also ruby-head backtrace:

```
BUG] Segmentation fault at 0x0000000000000008
ruby 3.4.0dev (2024-01-24T10:33:25Z master 0f417d640d) [x86_64-linux]
-- Control frame information -----------------------------------------------
c:0003 p:---- s:0012 e:000011 CFUNC  :match?
c:0002 p:0007 s:0007 e:000005 EVAL   -:1 [FINISH]
c:0001 p:0000 s:0003 E:001010 DUMMY  [FINISH]
-- Ruby level backtrace information ----------------------------------------
-:1:in `<main>'
-:1:in `match?'
-- Threading information ---------------------------------------------------
Total ractor count: 1
Ruby thread count for this ractor: 1
-- Machine register context ------------------------------------------------
RIP: 0x00007f7d2e74dfbd RBP: 0x00007ffec7b14a40 RSP: 0x00007ffec7b12a20
RAX: 0x0000000000000008 RBX: 0x00007ffec7b14aa0 RCX: 0x0000000000000000
RDX: 0x0000000000000002 RDI: 0x0000000000000008 RSI: 0x0000000000000008
 R8: 0x00007ffec7b14980  R9: 0x0000000000000001 R10: 0x00005572ce2d8391
R11: 0x0000000000000009 R12: 0x0000000000000000 R13: 0x00005572ce05d500
R14: 0x0000000000000004 R15: 0x00007ffec7b12100 EFL: 0x0000000000010297
-- C level backtrace information -------------------------------------------
/opt/ruby/lib/libruby.so.3.4(rb_print_backtrace+0x14) [0x7f7d2e824371] /ruby/vm_dump.c:820
/opt/ruby/lib/libruby.so.3.4(rb_vm_bugreport) /ruby/vm_dump.c:1151
/opt/ruby/lib/libruby.so.3.4(rb_bug_for_fatal_signal+0x104) [0x7f7d2e617984] /ruby/error.c:1065
/opt/ruby/lib/libruby.so.3.4(sigsegv+0x4d) [0x7f7d2e76fbdd] /ruby/signal.c:926
/lib/x86_64-linux-gnu/libc.so.6(0x7f7d2e152520) [0x7f7d2e152520]
/opt/ruby/lib/libruby.so.3.4(match_at+0x60d) [0x7f7d2e74dfbd] /ruby/regexec.c:4125
/opt/ruby/lib/libruby.so.3.4(onig_search_gpos+0x67d) [0x7f7d2e757d9d] /ruby/regexec.c:5370
/opt/ruby/lib/libruby.so.3.4(onig_search+0x1a) [0x7f7d2e75827a] /ruby/regexec.c:5099
/opt/ruby/lib/libruby.so.3.4(reg_onig_search+0x42) [0x7f7d2e734792] /ruby/re.c:1725
/opt/ruby/lib/libruby.so.3.4(rb_reg_onig_match+0x93) [0x7f7d2e739243] /ruby/re.c:1661
/opt/ruby/lib/libruby.so.3.4(rb_reg_match_p+0xfb) [0x7f7d2e73b96b] /ruby/re.c:3824
/opt/ruby/lib/libruby.so.3.4(vm_cfp_consistent_p+0x0) [0x7f7d2e7f5dc4] /ruby/vm_insnhelper.c:3492
```


----------------------------------------
Bug #20207: Segmentation fault for a regexp containing positive and negative lookaheads
https://bugs.ruby-lang.org/issues/20207#change-106431

* 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)


-- 
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