[ruby-core:107741] [Ruby master Bug#17382] Segfault in String#inspect

Issue #17382 has been updated by tom_dalling (Tom Dalling).

File segfault.rb added

I'm able to reproduce this by parsing and inspecting JSON in multiple threads (code attached), but only after booting our Rails app. I'm trying to make a reproducible example, but it is proving to be difficult.

----------------------------------------
Bug #17382: Segfault in String#inspect
https://bugs.ruby-lang.org/issues/17382#change-96666

* Author: lionelperrin (Lionel Perrin)
* Status: Closed
* Priority: Normal
* ruby -v: ruby 2.7.2p137 (2020-10-01 revision 5445e04352) [x86_64-linux]
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
Hello,

We experienced a segfault in our application. It seems that it happened right after we've upgraded from ruby 2.6 to ruby 2.7.2.
The faulting ruby code is actionpack-6.0.3.4/lib/action_controller/log_subscriber.rb:16:
``` ruby
info "  Parameters: #{params.inspect}" unless params.empty?
```
However, the problem seems to be due to string.c:10702

Here is an extract of the output from ruby (full output attached):
``` shell
-- Control frame information -----------------------------------------------
c:0073 p:---- s:0500 e:000499 CFUNC  :inspect
c:0072 p:---- s:0497 e:000496 CFUNC  :inspect
c:0071 p:0137 s:0493 e:000490 METHOD /usr/app/rubygems/ruby/2.7.0/gems/actionpack-6.0.3.4/lib/action_controller/log_subscriber.rb:16
c:0070 p:0038 s:0483 e:000482 METHOD /usr/app/rubygems/ruby/2.7.0/gems/activesupport-6.0.3.4/lib/active_support/subscriber.rb:145
...
-- Ruby level backtrace information ----------------------------------------
/usr/app/rubygems/ruby/2.7.0/gems/puma-5.0.4/lib/puma/thread_pool.rb:145:in `block in spawn_thread'
/usr/app/rubygems/ruby/2.7.0/gems/puma-5.0.4/lib/puma/server.rb:430:in `process_client'
/usr/app/rubygems/ruby/2.7.0/gems/puma-5.0.4/lib/puma/request.rb:75:in `handle_request'
...
-- Machine register context ------------------------------------------------
 RIP: 0x00007fd7ab8b0f5c RBP: 0x00007fd7844b92c8 RSP: 0x00007fd7a4af7fe0
 RAX: 0x00005597fb1672c0 RBX: 0x0000000000000000 RCX: 0x00007fd7ab8b1060
 RDX: 0x0000000000000000 RDI: 0x0000000000000000 RSI: 0x0000000000000000
  R8: 0x00007fd7a4bf8d50  R9: 0x00005597ffce6378 R10: 0x0000000055550083
 R11: 0x0000000000000000 R12: 0x0000000000000000 R13: 0x00005597fb1b0038
 R14: 0x00005597fb1672c0 R15: 0x0000000000000000 EFL: 0x0000000000010206
-- C level backtrace information -------------------------------------------
/usr/local/lib/libruby.so.2.7(rb_vm_bugreport+0x555) [0x7fd7ab9176f5] vm_dump.c:755
[0x7fd7ab756427]
/usr/local/lib/libruby.so.2.7(sigsegv+0x4b) [0x7fd7ab88311b] signal.c:946
/lib/x86_64-linux-gnu/libpthread.so.0(__restore_rt+0x0) [0x7fd7ab45f730]
/usr/local/lib/libruby.so.2.7(rb_str_symname_p+0x1c) [0x7fd7ab8b0f5c] string.c:10702
/usr/local/lib/libruby.so.2.7(sym_inspect+0x1a) [0x7fd7ab8b107a] string.c:10761
[0x7fd7ab909271]
/usr/local/lib/libruby.so.2.7(rb_funcallv_with_cc+0x118) [0x7fd7ab90bb68] vm_eval.c:1013
```


---Files--------------------------------
ruby_segfault_log.txt (86.2 KB)
segfault.rb (1.03 KB)


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