[ruby-core:121435] [Ruby Bug#21195] Crash when using IO#timeout

22 Mar 2025

      Issue #21195 has been updated by ioquatix (Samuel Williams).

@mame your reproduction is extremely useful, thanks.

The fix you provided isn't quite right, I believe the correct fix is <https://github.com/ruby/ruby/pull/12961>.

----------------------------------------
Bug #21195: Crash when using IO#timeout
https://bugs.ruby-lang.org/issues/21195#change-112415

* Author: nickamorim (Nick Amorim)
* Status: Assigned
* Assignee: ioquatix (Samuel Williams)
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
We have adopted the [IO#timeout](https://bugs.ruby-lang.org/issues/18630) feature in Dalli ([ref](https://github.com/petergoldstein/dalli/pull/1025)) for I/O timeouts. We regularly see crashes in our CI environment that I was able to pinpoint to calling `IO#gets` with `IO#timeout`:

## C Backtrace

```
_bk;t=1742524358337-- Threading information ---------------------------------------------------
_bk;t=1742524358337Total ractor count: 1
_bk;t=1742524358337Ruby thread count for this ractor: 10
_bk;t=1742524358337
_bk;t=1742524358337-- C level backtrace information -------------------------------------------
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_print_backtrace+0x8) [0x798534ef70c2] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_dump.c:823
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_vm_bugreport) /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_dump.c:1155
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_bug_without_die_internal+0x6b) [0x798534bf99b1] /tmp/ruby-build/ruby-3.4.2-pshopify2/error.c:1097
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_bug) /tmp/ruby-build/ruby-3.4.2-pshopify2/error.c:1115
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_syserr_new_path_in+0x30) [0x798534bf9ea2] /tmp/ruby-build/ruby-3.4.2-pshopify2/error.c:3927
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_syserr_fail_path_in+0xf) [0x798534cd8daf] /tmp/ruby-build/ruby-3.4.2-pshopify2/error.c:3915
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(io_fillbuf+0x99) [0x798534d22679] /tmp/ruby-build/ruby-3.4.2-pshopify2/io.c:2642
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(appendline+0x3d) [0x798534d250d5] /tmp/ruby-build/ruby-3.4.2-pshopify2/io.c:3954
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_io_getline_0) /tmp/ruby-build/ruby-3.4.2-pshopify2/io.c:4215
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_io_getline_1+0x21) [0x798534d25edb] /tmp/ruby-build/ruby-3.4.2-pshopify2/io.c:4273
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_io_getline) /tmp/ruby-build/ruby-3.4.2-pshopify2/io.c:4293
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_io_gets_m) /tmp/ruby-build/ruby-3.4.2-pshopify2/io.c:4387
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_call_cfunc_with_frame_+0x11f) [0x798534ecd7af] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_insnhelper.c:3794
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_sendish+0xbb) [0x798534ed6e6c] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_insnhelper.c:5961
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_exec_core) /tmp/ruby-build/ruby-3.4.2-pshopify2/insns.def:898
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_vm_exec+0x189) [0x798534ede289] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:2595
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_yield_values2+0x63) [0x798534ee2be3] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:1676
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_ensure+0xe6) [0x798534ce1116] /tmp/ruby-build/ruby-3.4.2-pshopify2/eval.c:1074
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_call_cfunc_with_frame_+0x11f) [0x798534ecd7af] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_insnhelper.c:3794
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_sendish+0xd3) [0x798534ec6da3] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_insnhelper.c:5961
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_exec_core+0x1151) [0x798534ed7e71] /tmp/ruby-build/ruby-3.4.2-pshopify2/insns.def:851
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_vm_exec+0x189) [0x798534ede289] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:2595
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_yield_with_cref+0x42) [0x798534ee3348] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:1676
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_yield) /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:1684
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_yield_0) /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_eval.c:1344
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_yield) /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_eval.c:1360
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_ary_collect+0x5c) [0x798534c1010c] /tmp/ruby-build/ruby-3.4.2-pshopify2/array.c:3645
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_call_cfunc_with_frame_+0x11f) [0x798534ecd7af] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_insnhelper.c:3794
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_sendish+0xd3) [0x798534ec6da3] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_insnhelper.c:5961
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_exec_core+0x1151) [0x798534ed7e71] /tmp/ruby-build/ruby-3.4.2-pshopify2/insns.def:851
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_vm_exec+0x189) [0x798534ede289] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:2595
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_yield_with_cref+0x42) [0x798534ee3348] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:1676
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_yield) /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:1684
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_yield_0) /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_eval.c:1344
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_yield) /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_eval.c:1360
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(RB_FL_TEST_RAW+0x0) [0x798534c0951c] /tmp/ruby-build/ruby-3.4.2-pshopify2/array.c:2641
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(RB_FL_ANY_RAW) ./include/ruby/internal/fl_type.h:520
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_array_len) ./include/ruby/internal/core/rarray.h:259
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_ary_each) /tmp/ruby-build/ruby-3.4.2-pshopify2/array.c:2640
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_call_cfunc_with_frame_+0x11f) [0x798534ecd7af] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_insnhelper.c:3794
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_sendish+0xd3) [0x798534ec6da3] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm_insnhelper.c:5961
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_exec_core+0x1151) [0x798534ed7e71] /tmp/ruby-build/ruby-3.4.2-pshopify2/insns.def:851
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(vm_exec_loop+0xa) [0x798534ede529] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:2622
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_vm_exec) /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:2601
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_vm_invoke_proc+0x66) [0x798534edf276] /tmp/ruby-build/ruby-3.4.2-pshopify2/vm.c:1770
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_proc_call_kw+0x6a) [0x798534dc825a] /tmp/ruby-build/ruby-3.4.2-pshopify2/proc.c:988
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(exec_end_procs_chain+0x44) [0x798534ce25cd] /tmp/ruby-build/ruby-3.4.2-pshopify2/eval_jump.c:105
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_ec_exec_end_proc) /tmp/ruby-build/ruby-3.4.2-pshopify2/eval_jump.c:121
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_ec_teardown+0xcc) [0x798534ce27bc] /tmp/ruby-build/ruby-3.4.2-pshopify2/eval.c:155
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(rb_ec_cleanup+0x144) [0x798534ce29f4] /tmp/ruby-build/ruby-3.4.2-pshopify2/eval.c:207
_bk;t=1742524358649/usr/local/ruby/lib/libruby.so.3.4(ruby_run_node+0x8d) [0x798534ce2e1d] /tmp/ruby-build/ruby-3.4.2-pshopify2/eval.c:319
```

## Ruby Backtrace
```
_bk;t=1742524358337/tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/protocol/connection_manager.rb:157: [BUG] rb_sys_fail_path_in(io_fillbuf, fd:16 ) - errno == 0
_bk;t=1742524358337ruby 3.4.2 (2025-03-18 revision 20130836d0) +PRISM [x86_64-linux]
_bk;t=1742524358337
_bk;t=1742524358337-- Control frame information -----------------------------------------------
_bk;t=1742524358337c:0042 p:---- s:0206 e:000205 CFUNC  :gets
_bk;t=1742524358337c:0041 p:0007 s:0201 e:000200 METHOD /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/protocol/connection_manager.rb:157
_bk;t=1742524358337c:0040 p:0005 s:0195 e:000194 METHOD /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/protocol/meta/response_processor.rb:242
_bk;t=1742524358337c:0039 p:0003 s:0191 e:000190 METHOD /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/protocol/meta/response_processor.rb:246
_bk;t=1742524358337c:0038 p:0003 s:0186 e:000185 METHOD /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/protocol/meta/response_processor.rb:186
_bk;t=1742524358337c:0037 p:0007 s:0180 e:000179 METHOD /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/protocol/meta/response_processor.rb:108
_bk;t=1742524358337c:0036 p:0025 s:0176 e:000175 METHOD /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/protocol/meta.rb:232
_bk;t=1742524358337c:0035 p:0021 s:0171 e:000170 METHOD /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/protocol/base.rb:37
_bk;t=1742524358337c:0034 p:0010 s:0163 e:000162 BLOCK  /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/options.rb:18 [FINISH]
_bk;t=1742524358337c:0033 p:---- s:0160 e:000159 CFUNC  :synchronize
_bk;t=1742524358337c:0032 p:0006 s:0156 e:000155 METHOD /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/options.rb:17
_bk;t=1742524358337c:0031 p:0008 s:0150 e:000149 BLOCK  /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/client.rb:324 [FINISH]
_bk;t=1742524358337c:0030 p:---- s:0146 e:000145 CFUNC  :map
_bk;t=1742524358337c:0029 p:0011 s:0142 e:000141 METHOD /tmp/bundle/ruby/3.4.0/bundler/gems/dalli-fbd3cba210d9/lib/dalli/client.rb:324
```

Unfortunately, I was not able to build a reproducible test. I have tried running on both Ruby 3.4.1 and 3.4.2 with no luck. The crash happens here: https://github.com/Shopify/ruby/blob/v3.4.1-pshopify3/io.c#L2632-L2643.

Please let me know if there's any more information that I can provide :-)

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