* Fix use-after-free
This can easily glanced on valgrind:
$ cat a.rb
require 'mini_racer'
puts 'before context new'
context = MiniRacer::Context.new
puts 'after context new'
context.dispose
puts 'after dispose'
glopes ~/repos/mini_racer ((b32ca19...) %) $ valgrind --max-stackframe=8379104 /home/glopes/ruby/bin/ruby -Ilib:test:lib a.rb
==29861== Memcheck, a memory error detector
==29861== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==29861== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==29861== Command: /home/glopes/ruby/bin/ruby -Ilib:test:lib a.rb
==29861==
before context new
after context new
==29861== Invalid read of size 8
==29861== at 0xC301450: free_context(ContextInfo*) (mini_racer_extension.cc:1247)
==29861== by 0xC301516: rb_context_dispose(unsigned long) (mini_racer_extension.cc:1439)
==29861== by 0x2F5B39: vm_call_cfunc_with_frame (vm_insnhelper.c:2514)
==29861== by 0x2F5B39: vm_call_cfunc (vm_insnhelper.c:2539)
==29861== by 0x30FF4D: vm_call_method (vm_insnhelper.c:3053)
==29861== by 0x307CD4: vm_sendish (vm_insnhelper.c:4023)
==29861== by 0x307CD4: vm_exec_core (insns.def:801)
==29861== by 0x2FF7E7: rb_vm_exec (vm.c:1920)
==29861== by 0x3004DD: invoke_iseq_block_from_c (vm.c:1116)
==29861== by 0x3004DD: invoke_block_from_c_bh (vm.c:1134)
==29861== by 0x3004DD: vm_yield (vm.c:1179)
==29861== by 0x3004DD: rb_yield_0 (vm_eval.c:1227)
==29861== by 0x3004DD: rb_yield_1 (vm_eval.c:1233)
==29861== by 0x3004DD: rb_yield (vm_eval.c:1243)
==29861== by 0x136F60: rb_ensure (eval.c:1129)
==29861== by 0x2F5B39: vm_call_cfunc_with_frame (vm_insnhelper.c:2514)
==29861== by 0x2F5B39: vm_call_cfunc (vm_insnhelper.c:2539)
==29861== by 0x30FF4D: vm_call_method (vm_insnhelper.c:3053)
==29861== by 0x307D8A: vm_sendish (vm_insnhelper.c:4023)
==29861== by 0x307D8A: vm_exec_core (insns.def:782)
==29861== by 0x2FFE8E: rb_vm_exec (vm.c:1929)
==29861== Address 0xbd6e520 is 0 bytes inside a block of size 48 free'd
==29861== at 0x4C30D3B: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==29861== by 0x157D09: objspace_xfree (gc.c:10071)
==29861== by 0x157D09: ruby_sized_xfree (gc.c:10164)
==29861== by 0x157D09: ruby_xfree (gc.c:10171)
==29861== by 0xC3013CF: operator delete (mini_racer_extension.cc:84)
==29861== by 0xC3013CF: release (mini_racer_extension.cc:71)
==29861== by 0xC3013CF: free_context_raw(void*) (mini_racer_extension.cc:1221)
==29861== by 0xC301448: free_context(ContextInfo*) (mini_racer_extension.cc:1244)
==29861== by 0xC301516: rb_context_dispose(unsigned long) (mini_racer_extension.cc:1439)
==29861== by 0x2F5B39: vm_call_cfunc_with_frame (vm_insnhelper.c:2514)
==29861== by 0x2F5B39: vm_call_cfunc (vm_insnhelper.c:2539)
==29861== by 0x30FF4D: vm_call_method (vm_insnhelper.c:3053)
==29861== by 0x307CD4: vm_sendish (vm_insnhelper.c:4023)
==29861== by 0x307CD4: vm_exec_core (insns.def:801)
==29861== by 0x2FF7E7: rb_vm_exec (vm.c:1920)
==29861== by 0x3004DD: invoke_iseq_block_from_c (vm.c:1116)
==29861== by 0x3004DD: invoke_block_from_c_bh (vm.c:1134)
==29861== by 0x3004DD: vm_yield (vm.c:1179)
==29861== by 0x3004DD: rb_yield_0 (vm_eval.c:1227)
==29861== by 0x3004DD: rb_yield_1 (vm_eval.c:1233)
==29861== by 0x3004DD: rb_yield (vm_eval.c:1243)
==29861== by 0x136F60: rb_ensure (eval.c:1129)
==29861== by 0x2F5B39: vm_call_cfunc_with_frame (vm_insnhelper.c:2514)
==29861== by 0x2F5B39: vm_call_cfunc (vm_insnhelper.c:2539)
==29861== Block was alloc'd at
==29861== at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==29861== by 0x154BE3: objspace_xmalloc0 (gc.c:9860)
==29861== by 0xC3041D1: operator new (mini_racer_extension.cc:80)
==29861== by 0xC3041D1: rb_context_init_unsafe(unsigned long, unsigned long, unsigned long) (mini_racer_extension.cc:777)
==29861== by 0x2F5B39: vm_call_cfunc_with_frame (vm_insnhelper.c:2514)
==29861== by 0x2F5B39: vm_call_cfunc (vm_insnhelper.c:2539)
==29861== by 0x30FF4D: vm_call_method (vm_insnhelper.c:3053)
==29861== by 0x307CD4: vm_sendish (vm_insnhelper.c:4023)
==29861== by 0x307CD4: vm_exec_core (insns.def:801)
==29861== by 0x2FF7E7: rb_vm_exec (vm.c:1920)
==29861== by 0x3037B6: vm_call0_body (vm_eval.c:136)
==29861== by 0x303F7E: rb_vm_call0 (vm_eval.c:52)
==29861== by 0x3042CC: rb_vm_call_kw (vm_eval.c:268)
==29861== by 0x3048CF: rb_call0 (vm_eval.c:392)
==29861== by 0x304D73: rb_call (vm_eval.c:718)
==29861== by 0x304D73: rb_funcallv_kw (vm_eval.c:965)
==29861==
after dispose
* Fix shutdown crashes, make cleanup threads detached
Can be reproduced just by running the tests:
while /home/glopes/ruby/bin/ruby -Ilib:test:lib -I/home/glopes/ruby/lib/ruby/gems/2.7.0/gems/rake-10.5.0/lib /home/glopes/ruby/lib/ruby/gems/2.7.0/gems/rake-10.5.0/lib/rake/rake_test_loader.rb test/mini_racer_test.rb; do echo not yet; done
...
You have skipped tests. Run with --verbose for details.
Segmentation fault (core dumped)
glopes ~/repos/mini_racer ((b32ca19...) %) $ coredumpctl gdb
PID: 29454 (ruby)
UID: 1000 (glopes)
GID: 1000 (glopes)
Signal: 11 (SEGV)
Timestamp: Tue 2020-05-05 15:24:40 WEST (11s ago)
Command Line: /home/glopes/ruby/bin/ruby -Ilib:test:lib -I/home/glopes/ruby/lib/ruby/gems/2.7.0/gems/rake-10.5.0/lib /home/glopes/ruby/lib/ruby/gems/2.7.0/gems/rake-10.5.0/lib/rake/rake_test_loader.rb test/mini_racer_test.rb
Executable: /home/glopes/ruby/bin/ruby
Control Group: /user.slice/user-1000.slice/session-c2.scope
Unit: session-c2.scope
Slice: user-1000.slice
Session: c2
Owner UID: 1000 (glopes)
Boot ID: 64a5c179f6764f5f95498c75fd17be8e
Machine ID: 82e2fca72c474b2591af0e380dc4cead
Hostname: aorus
Storage: /var/lib/systemd/coredump/core.ruby.1000.64a5c179f6764f5f95498c75fd17be8e.29454.1588688680000000.lz4
Message: Process 29454 (ruby) of user 1000 dumped core.
Stack trace of thread 29491:
#0 0x0000563082fe9e60 n/a (n/a)
#1 0x00007fc11080ae2c n/a (/home/glopes/repos/mini_racer/lib/mini_racer_extension.so)
#2 0x00007fc110794b03 n/a (/home/glopes/repos/mini_racer/lib/mini_racer_extension.so)
#3 0x00007fc11082829e n/a (/home/glopes/repos/mini_racer/lib/mini_racer_extension.so)
#4 0x00007fc110827f76 n/a (/home/glopes/repos/mini_racer/lib/mini_racer_extension.so)
#5 0x00007fc1105e3560 n/a (/home/glopes/repos/mini_racer/lib/mini_racer_extension.so)
GNU gdb (Ubuntu 8.1-0ubuntu3.2) 8.1.0.20180409-git
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /home/glopes/ruby/bin/ruby...done.
[New LWP 29491]
[New LWP 29455]
[New LWP 29456]
[New LWP 29454]
[New LWP 29468]
[New LWP 29469]
[New LWP 29465]
[New LWP 29467]
[New LWP 29471]
[New LWP 29470]
[New LWP 29472]
[New LWP 29474]
[New LWP 29473]
[New LWP 29475]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/home/glopes/ruby/bin/ruby -Ilib:test:lib -I/home/glopes/ruby/lib/ruby/gems/2.7'.
Program terminated with signal SIGSEGV, Segmentation fault.
[Current thread is 1 (Thread 0x7fc0b0ff9700 (LWP 29491))]
#0 0x0000563082fe9e60 in ?? ()
#1 0x00007fc110b9ea6c in v8::internal::VirtualMemory::Free() () from /home/glopes/repos/mini_racer/lib/mini_racer_extension.so
#2 0x00007fc11080ae2c in v8::internal::StoreBuffer::TearDown() () from /home/glopes/repos/mini_racer/lib/mini_racer_extension.so
#3 0x00007fc110794b03 in v8::internal::Heap::TearDown() () from /home/glopes/repos/mini_racer/lib/mini_racer_extension.so
#4 0x00007fc11082829e in v8::internal::Isolate::Deinit() () from /home/glopes/repos/mini_racer/lib/mini_racer_extension.so
#5 0x00007fc110827f76 in v8::internal::Isolate::Delete(v8::internal::Isolate*) () from /home/glopes/repos/mini_racer/lib/mini_racer_extension.so
#6 0x00007fc1105e3560 in free_isolate (isolate_info=isolate_info@entry=0x563083e7db70) at ../../../../ext/mini_racer_extension/mini_racer_extension.cc:1194
#7 0x00007fc1105e03c8 in IsolateInfo::~IsolateInfo (this=0x563083e7db70, __in_chrg=<optimized out>)
at ../../../../ext/mini_racer_extension/mini_racer_extension.cc:52
#8 IsolateInfo::release (this=0x563083e7db70) at ../../../../ext/mini_racer_extension/mini_racer_extension.cc:71
#9 free_context_raw (arg=0x5630832a7d90) at ../../../../ext/mini_racer_extension/mini_racer_extension.cc:1221
#10 0x00007fc116c5f6db in start_thread (arg=0x7fc0b0ff9700) at pthread_create.c:463
#11 0x00007fc115d2588f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
2b1ee800ff