[ruby-core:121518] [Ruby Bug#21206] Segmentation fault on ISeq#to_binary

2 Apr 2025

      Issue #21206 has been updated by byroot (Jean Boussier).

I tracked it down to:

```c
            if (!p->it_id) {
                p->it_id = internal_id(p);
                vtable_add(p->lvtbl->args, p->it_id);
            }
```

Internal IDs can't be serialized.

It seems there was an attempt to fix this but it was reverted in https://github.com/ruby/ruby/commit/667a0f9f928

----------------------------------------
Bug #21206: Segmentation fault on ISeq#to_binary
https://bugs.ruby-lang.org/issues/21206#change-112543

* Author: shyouhei (Shyouhei Urabe)
* Status: Open
* ruby -v: ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +PRISM +GC [aarch64-linux-gnu]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Found this SEGV using bootsnap.

This could well be architecture dependent because of ISeqs being so by nature.

Also this doesn't happen when the ISeq is created using `compile_prism`.

```
$ ruby -ve 'RubyVM::InstructionSequence.compile_parsey("def f(g) = each {nil rescue g+it}").to_binary'
ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +PRISM +GC [aarch64-linux-gnu]
-e:1: [BUG] Segmentation fault at 0x0000000000000000
ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +PRISM +GC [aarch64-linux-gnu]

-- Control frame information -----------------------------------------------
c:0003 p:---- s:0010 e:000009 CFUNC  :to_binary
c:0002 p:0008 s:0006 e:000005 EVAL   -e:1 [FINISH]
c:0001 p:0000 s:0003 E:000190 DUMMY  [FINISH]

-- Ruby level backtrace information ----------------------------------------
-e:1:in '<main>'
-e:1:in 'to_binary'

-- Threading information ---------------------------------------------------
Total ractor count: 1
Ruby thread count for this ractor: 1

-- Machine register context ------------------------------------------------
  x0: 0x0000000000000000  x1: 0x0000ffff8a15d0a8  x2: 0x0000000000000000
  x3: 0x0000000000000003  x4: 0x0000000000000000  x5: 0x0000ffffa4346b50
  x6: 0x0000000000000005  x7: 0x00000000fffffffe x18: 0x000000000116810c
 x19: 0x0000ffff8a15d0a8 x20: 0x0000000000000000 x21: 0x0000000000000001
 x22: 0x0000ffffc0f0d968 x23: 0x0000ffffc0f0d4c0 x24: 0x0000000000000018
 x25: 0x0000ffffa3c98530 x26: 0x0000000000000000 x27: 0x0000000000000002
 x28: 0x0000ffffc0f0d4e8 x29: 0x0000ffffc0f0d410  sp: 0x0000ffffc0f0d410
 fau: 0x0000000000000000

-- C level backtrace information -------------------------------------------
/lib/aarch64-linux-gnu/libruby-3.4.so.3.4(0xffffa3e8ff84) [0xffffa3e8ff84]
/lib/aarch64-linux-gnu/libruby-3.4.so.3.4(0xffffa3e95514) [0xffffa3e95514]
/lib/aarch64-linux-gnu/libruby-3.4.so.3.4(0xffffa3ce760c) [0xffffa3ce760c]
/lib/aarch64-linux-gnu/libruby-3.4.so.3.4(0xffffa3e0de88) [0xffffa3e0de88]
linux-vdso.so.1(__kernel_rt_sigreturn+0x0) [0xffffa43447a0]
/lib/aarch64-linux-gnu/libruby-3.4.so.3.4(rb_str_cmp+0x24) [0xffffa3e17d94]
[0xffffa3980b9c]
[0xffffa3980efc]
[0xffffa3f418c8]
[0xffffa3c98d4c]
[0xffffa3da2484]
/lib/aarch64-linux-gnu/libruby-3.4.so.3.4(rb_st_foreach+0x44) [0xffffa3e06944]
[0xffffa3f213e4]
[0xffffa3d46ea4]
[0xffffa3e6c92c]
[0xffffa3e767a8]
[0xffffa3e8cae8]
[0xffffa3ce6ac4]
/lib/aarch64-linux-gnu/libruby-3.4.so.3.4(ruby_run_node+0x9c) [0xffffa3cebba0]
[0xaaaae2be0b30]
[0xffffa39684c4]
[0xffffa3968598]
[0xaaaae2be0bb0]

-- Other runtime information -----------------------------------------------

* Loaded script: -e

* Loaded features:

    0 enumerator.so
    1 thread.rb
    2 fiber.so
    3 rational.so
    4 complex.so
    5 ruby2_keywords.rb
    6 /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/encdb.so
    7 /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/trans/transdb.so
    8 /usr/lib/aarch64-linux-gnu/ruby/3.4.0/rbconfig.rb
    9 /usr/lib/ruby/3.4.0/rubygems/compatibility.rb
   10 /usr/lib/ruby/3.4.0/rubygems/defaults.rb
   11 /usr/lib/ruby/3.4.0/rubygems/deprecate.rb
   12 /usr/lib/ruby/3.4.0/rubygems/errors.rb
   13 /usr/lib/ruby/3.4.0/rubygems/target_rbconfig.rb
   14 /usr/lib/ruby/3.4.0/rubygems/unknown_command_spell_checker.rb
   15 /usr/lib/ruby/3.4.0/rubygems/exceptions.rb
   16 /usr/lib/ruby/3.4.0/rubygems/basic_specification.rb
   17 /usr/lib/ruby/3.4.0/rubygems/stub_specification.rb
   18 /usr/lib/ruby/3.4.0/rubygems/platform.rb
   19 /usr/lib/ruby/3.4.0/rubygems/specification_record.rb
   20 /usr/lib/ruby/3.4.0/rubygems/util/list.rb
   21 /usr/lib/ruby/3.4.0/rubygems/version.rb
   22 /usr/lib/ruby/3.4.0/rubygems/requirement.rb
   23 /usr/lib/ruby/3.4.0/rubygems/specification.rb
   24 /usr/lib/ruby/vendor_ruby/rubygems/defaults/operating_system.rb
   25 /usr/lib/ruby/3.4.0/rubygems/util.rb
   26 /usr/lib/ruby/3.4.0/rubygems/dependency.rb
   27 /usr/lib/ruby/3.4.0/rubygems/core_ext/kernel_gem.rb
   28 /usr/lib/aarch64-linux-gnu/ruby/3.4.0/monitor.so
   29 /usr/lib/ruby/3.4.0/monitor.rb
   30 /usr/lib/ruby/3.4.0/rubygems.rb
   31 /usr/lib/ruby/3.4.0/bundled_gems.rb
   32 /usr/lib/ruby/3.4.0/rubygems/path_support.rb
   33 /usr/lib/ruby/3.4.0/error_highlight/version.rb
   34 /usr/lib/ruby/3.4.0/error_highlight/base.rb
   35 /usr/lib/ruby/3.4.0/error_highlight/formatter.rb
   36 /usr/lib/ruby/3.4.0/error_highlight/core_ext.rb
   37 /usr/lib/ruby/3.4.0/error_highlight.rb
   38 /usr/lib/ruby/3.4.0/did_you_mean/version.rb
   39 /usr/lib/ruby/3.4.0/did_you_mean/core_ext/name_error.rb
   40 /usr/lib/ruby/3.4.0/did_you_mean/levenshtein.rb
   41 /usr/lib/ruby/3.4.0/did_you_mean/jaro_winkler.rb
   42 /usr/lib/ruby/3.4.0/did_you_mean/spell_checker.rb
   43 /usr/lib/ruby/3.4.0/did_you_mean/spell_checkers/name_error_checkers/class_name_checker.rb
   44 /usr/lib/ruby/3.4.0/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb
   45 /usr/lib/ruby/3.4.0/did_you_mean/spell_checkers/name_error_checkers.rb
   46 /usr/lib/ruby/3.4.0/did_you_mean/spell_checkers/method_name_checker.rb
   47 /usr/lib/ruby/3.4.0/did_you_mean/spell_checkers/key_error_checker.rb
   48 /usr/lib/ruby/3.4.0/did_you_mean/spell_checkers/null_checker.rb
   49 /usr/lib/ruby/3.4.0/did_you_mean/tree_spell_checker.rb
   50 /usr/lib/ruby/3.4.0/did_you_mean/spell_checkers/require_path_checker.rb
   51 /usr/lib/ruby/3.4.0/did_you_mean/spell_checkers/pattern_key_name_checker.rb
   52 /usr/lib/ruby/3.4.0/did_you_mean/formatter.rb
   53 /usr/lib/ruby/3.4.0/did_you_mean.rb
   54 /usr/lib/ruby/3.4.0/syntax_suggest/core_ext.rb

* Process memory map:

aaaae2be0000-aaaae2be1000 r-xp 00000000 00:34 763738                     /usr/bin/ruby3.4
aaaae2bff000-aaaae2c00000 r--p 0000f000 00:34 763738                     /usr/bin/ruby3.4
aaaae2c00000-aaaae2c01000 rw-p 00010000 00:34 763738                     /usr/bin/ruby3.4
aaab18253000-aaab18545000 rw-p 00000000 00:00 0                          [heap]
ffff87c00000-ffff881f3000 r--s 00000000 00:34 763745                     /usr/lib/aarch64-linux-gnu/libruby-3.4.so.3.4.2
ffff88200000-ffff88201000 ---p 00000000 00:00 0 
ffff88201000-ffff882a2000 rw-p 00000000 00:00 0 
ffff882a2000-ffff882a3000 ---p 00000000 00:00 0 
ffff882a3000-ffff88344000 rw-p 00000000 00:00 0 
ffff88344000-ffff88345000 ---p 00000000 00:00 0 
ffff88345000-ffff883e6000 rw-p 00000000 00:00 0 
ffff883e6000-ffff883e7000 ---p 00000000 00:00 0 
ffff883e7000-ffff88488000 rw-p 00000000 00:00 0 
ffff88488000-ffff88489000 ---p 00000000 00:00 0 
ffff88489000-ffff8852a000 rw-p 00000000 00:00 0 
ffff8852a000-ffff8852b000 ---p 00000000 00:00 0 
ffff8852b000-ffff885cc000 rw-p 00000000 00:00 0 
ffff885cc000-ffff885cd000 ---p 00000000 00:00 0 
ffff885cd000-ffff8866e000 rw-p 00000000 00:00 0 
ffff8866e000-ffff8866f000 ---p 00000000 00:00 0 
ffff8866f000-ffff88710000 rw-p 00000000 00:00 0 
ffff88710000-ffff88711000 ---p 00000000 00:00 0 
ffff88711000-ffff887b2000 rw-p 00000000 00:00 0 
ffff887b2000-ffff887b3000 ---p 00000000 00:00 0 
ffff887b3000-ffff88854000 rw-p 00000000 00:00 0 
ffff88854000-ffff88855000 ---p 00000000 00:00 0 
ffff88855000-ffff888f6000 rw-p 00000000 00:00 0 
ffff888f6000-ffff888f7000 ---p 00000000 00:00 0 
ffff888f7000-ffff88998000 rw-p 00000000 00:00 0 
ffff88998000-ffff88999000 ---p 00000000 00:00 0 
ffff88999000-ffff88a3a000 rw-p 00000000 00:00 0 
ffff88a3a000-ffff88a3b000 ---p 00000000 00:00 0 
ffff88a3b000-ffff88adc000 rw-p 00000000 00:00 0 
ffff88adc000-ffff88add000 ---p 00000000 00:00 0 
ffff88add000-ffff88b7e000 rw-p 00000000 00:00 0 
ffff88b7e000-ffff88b7f000 ---p 00000000 00:00 0 
ffff88b7f000-ffff88c20000 rw-p 00000000 00:00 0 
ffff88c20000-ffff88c21000 ---p 00000000 00:00 0 
ffff88c21000-ffff88cc2000 rw-p 00000000 00:00 0 
ffff88cc2000-ffff88cc3000 ---p 00000000 00:00 0 
ffff88cc3000-ffff88d64000 rw-p 00000000 00:00 0 
ffff88d64000-ffff88d65000 ---p 00000000 00:00 0 
ffff88d65000-ffff88e06000 rw-p 00000000 00:00 0 
ffff88e06000-ffff88e07000 ---p 00000000 00:00 0 
ffff88e07000-ffff88ea8000 rw-p 00000000 00:00 0 
ffff88ea8000-ffff88ea9000 ---p 00000000 00:00 0 
ffff88ea9000-ffff88f4a000 rw-p 00000000 00:00 0 
ffff88f4a000-ffff88f4b000 ---p 00000000 00:00 0 
ffff88f4b000-ffff88fec000 rw-p 00000000 00:00 0 
ffff88fec000-ffff88fed000 ---p 00000000 00:00 0 
ffff88fed000-ffff8908e000 rw-p 00000000 00:00 0 
ffff8908e000-ffff8908f000 ---p 00000000 00:00 0 
ffff8908f000-ffff89130000 rw-p 00000000 00:00 0 
ffff89130000-ffff89131000 ---p 00000000 00:00 0 
ffff89131000-ffff891d2000 rw-p 00000000 00:00 0 
ffff891d2000-ffff891d3000 ---p 00000000 00:00 0 
ffff891d3000-ffff89274000 rw-p 00000000 00:00 0 
ffff89274000-ffff89275000 ---p 00000000 00:00 0 
ffff89275000-ffff89316000 rw-p 00000000 00:00 0 
ffff89316000-ffff89317000 ---p 00000000 00:00 0 
ffff89317000-ffff893b8000 rw-p 00000000 00:00 0 
ffff893b8000-ffff893b9000 ---p 00000000 00:00 0 
ffff893b9000-ffff8945a000 rw-p 00000000 00:00 0 
ffff8945a000-ffff8945b000 ---p 00000000 00:00 0 
ffff8945b000-ffff894fc000 rw-p 00000000 00:00 0 
ffff894fc000-ffff894fd000 ---p 00000000 00:00 0 
ffff894fd000-ffff8959e000 rw-p 00000000 00:00 0 
ffff8959e000-ffff8959f000 ---p 00000000 00:00 0 
ffff8959f000-ffff89640000 rw-p 00000000 00:00 0 
ffff89800000-ffff89810000 ---p 00000000 00:00 0 
ffff89810000-ffff8a010000 rw-p 00000000 00:00 0 
ffff8a0d0000-ffff8a0e0000 rw-p 00000000 00:00 0 
ffff8a0ef000-ffff8a120000 rw-p 00000000 00:00 0 
ffff8a120000-ffff8a122000 r-xp 00000000 00:34 763838                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/monitor.so
ffff8a122000-ffff8a13f000 ---p 00002000 00:34 763838                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/monitor.so
ffff8a13f000-ffff8a140000 r--p 0000f000 00:34 763838                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/monitor.so
ffff8a140000-ffff8a141000 rw-p 00010000 00:34 763838                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/monitor.so
ffff8a150000-ffffa3600000 rw-p 00000000 00:00 0 
ffffa3610000-ffffa36d0000 rw-p 00000000 00:00 0 
ffffa36d0000-ffffa36d2000 r-xp 00000000 00:34 763811                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/trans/transdb.so
ffffa36d2000-ffffa36ef000 ---p 00002000 00:34 763811                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/trans/transdb.so
ffffa36ef000-ffffa36f0000 r--p 0000f000 00:34 763811                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/trans/transdb.so
ffffa36f0000-ffffa36f1000 rw-p 00010000 00:34 763811                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/trans/transdb.so
ffffa3700000-ffffa3710000 rw-p 00000000 00:00 0 
ffffa3710000-ffffa3712000 r-xp 00000000 00:34 763767                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/encdb.so
ffffa3712000-ffffa372f000 ---p 00002000 00:34 763767                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/encdb.so
ffffa372f000-ffffa3730000 r--p 0000f000 00:34 763767                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/encdb.so
ffffa3730000-ffffa3731000 rw-p 00010000 00:34 763767                     /usr/lib/aarch64-linux-gnu/ruby/3.4.0/enc/encdb.so
ffffa3740000-ffffa3790000 rw-p 00000000 00:00 0 
ffffa379e000-ffffa3900000 rw-p 00000000 00:00 0 
ffffa3900000-ffffa391f000 r-xp 00000000 00:34 566619                     /usr/lib/aarch64-linux-gnu/libgcc_s.so.1
ffffa391f000-ffffa392f000 ---p 0001f000 00:34 566619                     /usr/lib/aarch64-linux-gnu/libgcc_s.so.1
ffffa392f000-ffffa3930000 r--p 0001f000 00:34 566619                     /usr/lib/aarch64-linux-gnu/libgcc_s.so.1
ffffa3930000-ffffa3931000 rw-p 00020000 00:34 566619                     /usr/lib/aarch64-linux-gnu/libgcc_s.so.1
ffffa3940000-ffffa3ada000 r-xp 00000000 00:34 770271                     /usr/lib/aarch64-linux-gnu/libc.so.6
ffffa3ada000-ffffa3aed000 ---p 0019a000 00:34 770271                     /usr/lib/aarch64-linux-gnu/libc.so.6
ffffa3aed000-ffffa3af0000 r--p 0019d000 00:34 770271                     /usr/lib/aarch64-linux-gnu/libc.so.6
ffffa3af0000-ffffa3af2000 rw-p 001a0000 00:34 770271                     /usr/lib/aarch64-linux-gnu/libc.so.6
ffffa3af2000-ffffa3afe000 rw-p 00000000 00:00 0 
ffffa3b00000-ffffa3b85000 r-xp 00000000 00:34 770303                     /usr/lib/aarch64-linux-gnu/libm.so.6
ffffa3b85000-ffffa3b9f000 ---p 00085000 00:34 770303                     /usr/lib/aarch64-linux-gnu/libm.so.6
ffffa3b9f000-ffffa3ba0000 r--p 0008f000 00:34 770303                     /usr/lib/aarch64-linux-gnu/libm.so.6
ffffa3ba0000-ffffa3ba1000 rw-p 00090000 00:34 770303                     /usr/lib/aarch64-linux-gnu/libm.so.6
ffffa3bb0000-ffffa3bdd000 r-xp 00000000 00:34 566603                     /usr/lib/aarch64-linux-gnu/libcrypt.so.1.1.0
ffffa3bdd000-ffffa3bef000 ---p 0002d000 00:34 566603                     /usr/lib/aarch64-linux-gnu/libcrypt.so.1.1.0
ffffa3bef000-ffffa3bf0000 r--p 0002f000 00:34 566603                     /usr/lib/aarch64-linux-gnu/libcrypt.so.1.1.0
ffffa3bf0000-ffffa3bf1000 rw-p 00030000 00:34 566603                     /usr/lib/aarch64-linux-gnu/libcrypt.so.1.1.0
ffffa3bf1000-ffffa3bf9000 rw-p 00000000 00:00 0 
ffffa3c00000-ffffa41cb000 r-xp 00000000 00:34 763745                     /usr/lib/aarch64-linux-gnu/libruby-3.4.so.3.4.2
ffffa41cb000-ffffa41d6000 ---p 005cb000 00:34 763745                     /usr/lib/aarch64-linux-gnu/libruby-3.4.so.3.4.2
ffffa41d6000-ffffa41f0000 r--p 005d6000 00:34 763745                     /usr/lib/aarch64-linux-gnu/libruby-3.4.so.3.4.2
ffffa41f0000-ffffa41f1000 rw-p 005f0000 00:34 763745                     /usr/lib/aarch64-linux-gnu/libruby-3.4.so.3.4.2
ffffa41f1000-ffffa4206000 rw-p 00000000 00:00 0 
ffffa420f000-ffffa4220000 r--s 00000000 00:34 763738                     /usr/bin/ruby3.4
ffffa4220000-ffffa4230000 rw-p 00000000 00:00 0 
ffffa4230000-ffffa42aa000 r-xp 00000000 00:34 767074                     /usr/lib/aarch64-linux-gnu/libgmp.so.10.5.0
ffffa42aa000-ffffa42bf000 ---p 0007a000 00:34 767074                     /usr/lib/aarch64-linux-gnu/libgmp.so.10.5.0
ffffa42bf000-ffffa42c0000 r--p 0007f000 00:34 767074                     /usr/lib/aarch64-linux-gnu/libgmp.so.10.5.0
ffffa42c0000-ffffa42c1000 rw-p 00080000 00:34 767074                     /usr/lib/aarch64-linux-gnu/libgmp.so.10.5.0
ffffa42d0000-ffffa42ea000 r-xp 00000000 00:34 566707                     /usr/lib/aarch64-linux-gnu/libz.so.1.3
ffffa42ea000-ffffa42ff000 ---p 0001a000 00:34 566707                     /usr/lib/aarch64-linux-gnu/libz.so.1.3
ffffa42ff000-ffffa4300000 r--p 0001f000 00:34 566707                     /usr/lib/aarch64-linux-gnu/libz.so.1.3
ffffa4300000-ffffa4301000 rw-p 00020000 00:34 566707                     /usr/lib/aarch64-linux-gnu/libz.so.1.3
ffffa4307000-ffffa432e000 r-xp 00000000 00:34 769991                     /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1
ffffa4339000-ffffa433d000 rw-p 00000000 00:00 0 
ffffa4340000-ffffa4342000 rw-p 00000000 00:00 0 
ffffa4342000-ffffa4344000 r--p 00000000 00:00 0                          [vvar]
ffffa4344000-ffffa4345000 r-xp 00000000 00:00 0                          [vdso]
ffffa4345000-ffffa4347000 r--p 0002e000 00:34 769991                     /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1
ffffa4347000-ffffa4349000 rw-p 00030000 00:34 769991                     /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1
ffffc0eef000-ffffc0f10000 rw-p 00000000 00:00 0                          [stack]

Segmentation fault
```

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