Declarative marking of RTypedData struct references #11
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chrisseaton
reviewed
Jul 22, 2022
|
This is the general idea as I understood it, yes. |
chrisseaton
pushed a commit
that referenced
this pull request
Nov 6, 2022
Always look up instance variable buffers when iterating. It is possible for the instance variable buffer to change out from under the object during iteration, so we cannot cache the buffer on the stack. In the case of Bug #19095, the transient heap moved the buffer during iteration: ``` Watchpoint 1 hit: old value: 0x0000000107c00df8 new value: 0x00000001032743c0 Process 31720 stopped * thread #1, queue = 'com.apple.main-thread', stop reason = watchpoint 1 frame #0: 0x00000001006e5178 miniruby`rb_obj_transient_heap_evacuate(obj=0x000000010d6b94b0, promote=1) at variable.c:1361:5 1358 } 1359 MEMCPY(new_ptr, old_ptr, VALUE, len); 1360 ROBJECT(obj)->as.heap.ivptr = new_ptr; -> 1361 } 1362 } 1363 #endif 1364 miniruby`rb_obj_transient_heap_evacuate: -> 0x1006e5178 <+328>: b 0x1006e517c ; <+332> at variable.c:1362:1 0x1006e517c <+332>: ldp x29, x30, [sp, #0x50] 0x1006e5180 <+336>: add sp, sp, #0x60 0x1006e5184 <+340>: ret Target 0: (miniruby) stopped. (lldb) bt * thread #1, queue = 'com.apple.main-thread', stop reason = watchpoint 1 * frame #0: 0x00000001006e5178 miniruby`rb_obj_transient_heap_evacuate(obj=0x000000010d6b94b0, promote=1) at variable.c:1361:5 frame #1: 0x00000001006cb150 miniruby`transient_heap_block_evacuate(theap=0x0000000100b196c0, block=0x0000000107c00000) at transient_heap.c:734:17 frame #2: 0x00000001006c854c miniruby`transient_heap_evacuate(dmy=0x0000000000000000) at transient_heap.c:808:17 frame #3: 0x00000001007fe6c0 miniruby`rb_postponed_job_flush(vm=0x0000000104402900) at vm_trace.c:1773:21 frame #4: 0x0000000100637a84 miniruby`rb_threadptr_execute_interrupts(th=0x0000000103803bc0, blocking_timing=0) at thread.c:2316:13 frame #5: 0x000000010078b730 miniruby`rb_vm_check_ints(ec=0x00000001048038d0) at vm_core.h:2025:9 frame #6: 0x00000001006fbd10 miniruby`vm_pop_frame(ec=0x00000001048038d0, cfp=0x0000000104a04440, ep=0x0000000104904a28) at vm_insnhelper.c:422:5 frame #7: 0x00000001006fbca0 miniruby`rb_vm_pop_frame(ec=0x00000001048038d0) at vm_insnhelper.c:431:5 frame #8: 0x00000001007d6420 miniruby`vm_call0_cfunc_with_frame(ec=0x00000001048038d0, calling=0x000000016fdcc6a0, argv=0x0000000000000000) at vm_eval.c:153:9 frame #9: 0x00000001007d44cc miniruby`vm_call0_cfunc(ec=0x00000001048038d0, calling=0x000000016fdcc6a0, argv=0x0000000000000000) at vm_eval.c:164:12 frame #10: 0x0000000100766e80 miniruby`vm_call0_body(ec=0x00000001048038d0, calling=0x000000016fdcc6a0, argv=0x0000000000000000) at vm_eval.c:210:15 frame #11: 0x00000001007d76f0 miniruby`vm_call0_cc(ec=0x00000001048038d0, recv=0x000000010d6b49d8, id=2769, argc=0, argv=0x0000000000000000, cc=0x000000010d6b2e58, kw_splat=0) at vm_eval.c:87:12 frame #12: 0x0000000100769e48 miniruby`rb_funcallv_scope(recv=0x000000010d6b49d8, mid=2769, argc=0, argv=0x0000000000000000, scope=CALL_FCALL) at vm_eval.c:1051:16 frame #13: 0x0000000100760a54 miniruby`rb_funcallv(recv=0x000000010d6b49d8, mid=2769, argc=0, argv=0x0000000000000000) at vm_eval.c:1066:12 frame #14: 0x000000010037513c miniruby`rb_inspect(obj=0x000000010d6b49d8) at object.c:633:34 frame #15: 0x000000010002c950 miniruby`inspect_ary(ary=0x000000010d6b4938, dummy=0x0000000000000000, recur=0) at array.c:3091:13 frame #16: 0x0000000100642020 miniruby`exec_recursive(func=(miniruby`inspect_ary at array.c:3084), obj=0x000000010d6b4938, pairid=0x0000000000000000, arg=0x0000000000000000, outer=0, mid=2769) at thread.c:5177:23 frame #17: 0x00000001006412fc miniruby`rb_exec_recursive(func=(miniruby`inspect_ary at array.c:3084), obj=0x000000010d6b4938, arg=0x0000000000000000) at thread.c:5205:12 frame #18: 0x00000001000127f0 miniruby`rb_ary_inspect(ary=0x000000010d6b4938) at array.c:3117:12 ``` In general though, any calls back out to the interpreter could change the IV buffer, so it's not safe to cache. [Bug #19095]
Bumps [rb-sys](https://github.com/oxidize-rb/rb-sys) from 0.9.54 to 0.9.56. - [Release notes](https://github.com/oxidize-rb/rb-sys/releases) - [Commits](oxidize-rb/rb-sys@v0.9.54...v0.9.56) --- updated-dependencies: - dependency-name: rb-sys dependency-type: direct:production update-type: version-update:semver-patch ... Signed-off-by: dependabot[bot] <[email protected]>
…22" for build host. checking whether make sets $(MAKE)... (cached) yes checking build system type... arm-apple-darwin21.6.0 checking host system type... Invalid configuration `arm64-apple-darwin21': machine `arm64-apple' not recognized configure: error: /bin/sh /Users/hsbt/Downloads/yaml-0.2.5/config/config.sub arm64-apple-darwin21 failed *** extconf.rb failed *** ruby/psych@ad1502202c
…builder/custom_name Bumps [rb-sys](https://github.com/oxidize-rb/rb-sys) from 0.9.54 to 0.9.56. - [Release notes](https://github.com/oxidize-rb/rb-sys/releases) - [Commits](oxidize-rb/rb-sys@v0.9.54...v0.9.56) --- updated-dependencies: - dependency-name: rb-sys dependency-type: direct:production update-type: version-update:semver-patch ... Signed-off-by: dependabot[bot] <[email protected]>
The interrupt check will unintentionally release the VM lock when loading an iseq. And this will cause issues with the `debug` gem's [`ObjectSpace.each_iseq` method](https://github.com/ruby/debug/blob/0fcfc28acae33ec1c08068fb7c33703cfa681fa7/ext/debug/iseq_collector.c#L61-L67), which wraps iseqs with a wrapper and exposes their internal states when they're actually not ready to be used. And when that happens, errors like this would occur and kill the `debug` gem's thread: ``` DEBUGGER: ReaderThreadError: uninitialized InstructionSequence ┃ DEBUGGER: Disconnected. ┃ ["/opt/rubies/ruby-3.2.0/lib/ruby/gems/3.2.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:247:in `absolute_path'", ┃ "/opt/rubies/ruby-3.2.0/lib/ruby/gems/3.2.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:247:in `block in iterate_iseq'", ┃ "/opt/rubies/ruby-3.2.0/lib/ruby/gems/3.2.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:246:in `each_iseq'", ... ``` A way to reproduce the issue is to satisfy these conditions at the same time: 1. `debug` gem calling `ObjectSpace.each_iseq` (e.g. [activating a `LineBreakpoint`](https://github.com/ruby/debug/blob/0fcfc28acae33ec1c08068fb7c33703cfa681fa7/lib/debug/breakpoint.rb#L246)). 2. A large amount of iseq being loaded from another thread (possibly through the `bootsnap` gem). 3. 1 and 2 iterating through the same iseq(s) at the same time. Because this issue requires external dependencies and a rather complicated timing setup to reproduce, I wasn't able to write a test case for it. But here's some pseudo code to help reproduce it: ```rb require "debug/session" Thread.new do 100.times do ObjectSpace.each_iseq do |iseq| iseq.absolute_path end end end sleep 0.1 load_a_bunch_of_iseq possibly_through_bootsnap ``` [Bug #19348] Co-authored-by: Peter Zhu <[email protected]>
… higher than max value
(ruby/reline#502) * multiline_repl do not need to depend on RubyLex * Add auto indent test
Use a commit at the top of RBS 2.8.3, not 3.0.0.dev.N.
Some chruby-related features and bug fixes.
Ignoring debug-1.7.1 because its extensions are not built. Try: gem pristine debug --version 1.7. Revert "Clear gem paths for each test" This reverts commit 6698b58.
RB_OBJ_WRITE already exists in rgengc.h, so we shouldn't redefine it in gc.h.
…rollbar rendeing test ruby/reline@268e02b155
…dering when dialog content is very long ruby/reline@d4c95f89ec
The function rb_hash_iter_lev doesn't exist as it was removed.
YJIT: implement codegen for String#empty?
Fewer cycles running nops when these jumps are not taken. Fixing all these so when they get copy pasted in the future we save on padding.
In Feature #19314, we concluded that the return value of String#bytesplice should be changed from the source string to the receiver, because the source string is useless and confusing when extra arguments are added. This change should be included in Ruby 3.2.1.
|
I'm going to investigate and try and benchmark this approach on top of Ruby master, so I'm closing this PR for now to avoid having a convoluted history on this fork. |
wks
pushed a commit
that referenced
this pull request
Aug 4, 2023
[Bug #19793]
Dummy frames are created at the top level when requiring another file.
While requiring a file, it will try to convert using encodings. Some of
these encodings will not respond to to_str. If method_missing is
redefined on Object, then it will call method_missing and attempt raise
an error. However, the iseq is invalid as it's a dummy frame so it will
write an invalid iseq to the created NoMethodError.
The following script crashes:
```
GC.stress = true
class Object
public :method_missing
end
File.write("/tmp/empty.rb", "")
require "/tmp/empty.rb"
```
With the following backtrace:
```
frame #0: 0x00000001000fa8b8 miniruby`RVALUE_MARKED(obj=4308637824) at gc.c:1638:12
frame #1: 0x00000001000fb440 miniruby`RVALUE_BLACK_P(obj=4308637824) at gc.c:1763:12
frame #2: 0x00000001000facdc miniruby`gc_writebarrier_incremental(a=4308637824, b=4308332208, objspace=0x000000010180b000) at gc.c:8822:9
frame #3: 0x00000001000faad8 miniruby`rb_gc_writebarrier(a=4308637824, b=4308332208) at gc.c:8864:17
frame #4: 0x000000010016aff0 miniruby`rb_obj_written(a=4308637824, oldv=36, b=4308332208, filename="../iseq.c", line=1279) at gc.h:804:9
frame #5: 0x0000000100162a60 miniruby`rb_obj_write(a=4308637824, slot=0x0000000100d09888, b=4308332208, filename="../iseq.c", line=1279) at gc.h:837:5
frame #6: 0x0000000100165b0c miniruby`iseqw_new(iseq=0x0000000100d09880) at iseq.c:1279:9
frame #7: 0x0000000100165a64 miniruby`rb_iseqw_new(iseq=0x0000000100d09880) at iseq.c:1289:12
frame #8: 0x00000001000d8324 miniruby`name_err_init_attr(exc=4309777920, recv=4304780496, method=827660) at error.c:1830:35
frame #9: 0x00000001000d1b80 miniruby`name_err_init(exc=4309777920, mesg=4308332496, recv=4304780496, method=827660) at error.c:1869:12
frame #10: 0x00000001000d1bd4 miniruby`rb_nomethod_err_new(mesg=4308332496, recv=4304780496, method=827660, args=4308332448, priv=0) at error.c:1957:5
frame #11: 0x000000010039049c miniruby`rb_make_no_method_exception(exc=4304914512, format=4308332496, obj=4304780496, argc=1, argv=0x000000016fdfab00, priv=0) at vm_eval.c:959:16
frame #12: 0x00000001003b3274 miniruby`raise_method_missing(ec=0x0000000100b06f40, argc=1, argv=0x000000016fdfab00, obj=4304780496, last_call_status=MISSING_NOENTRY) at vm_eval.c:999:15
frame #13: 0x00000001003945d4 miniruby`rb_method_missing(argc=1, argv=0x000000016fdfab00, obj=4304780496) at vm_eval.c:944:5
...
frame #23: 0x000000010038f5e4 miniruby`rb_vm_call_kw(ec=0x0000000100b06f40, recv=4304780496, id=2865, argc=1, argv=0x000000016fdfab00, me=0x0000000100cbfcf0, kw_splat=0) at vm_eval.c:326:12
frame #24: 0x00000001003c18e4 miniruby`call_method_entry(ec=0x0000000100b06f40, defined_class=4304927952, obj=4304780496, id=2865, cme=0x0000000100cbfcf0, argc=1, argv=0x000000016fdfab00, kw_splat=0) at vm_method.c:2720:20
frame #25: 0x00000001003c440c miniruby`check_funcall_exec(v=6171896792) at vm_eval.c:589:12
frame #26: 0x00000001000dec00 miniruby`rb_vrescue2(b_proc=(miniruby`check_funcall_exec at vm_eval.c:587), data1=6171896792, r_proc=(miniruby`check_funcall_failed at vm_eval.c:596), data2=6171896792, args="Pȗ") at eval.c:919:18
frame #27: 0x00000001000deab0 miniruby`rb_rescue2(b_proc=(miniruby`check_funcall_exec at vm_eval.c:587), data1=6171896792, r_proc=(miniruby`check_funcall_failed at vm_eval.c:596), data2=6171896792) at eval.c:900:17
frame #28: 0x000000010039008c miniruby`check_funcall_missing(ec=0x0000000100b06f40, klass=4304923536, recv=4304780496, mid=3233, argc=0, argv=0x0000000000000000, respond=-1, def=36, kw_splat=0) at vm_eval.c:666:15
frame #29: 0x000000010038fa60 miniruby`rb_check_funcall_default_kw(recv=4304780496, mid=3233, argc=0, argv=0x0000000000000000, def=36, kw_splat=0) at vm_eval.c:703:21
frame #30: 0x000000010038fb04 miniruby`rb_check_funcall(recv=4304780496, mid=3233, argc=0, argv=0x0000000000000000) at vm_eval.c:685:12
frame #31: 0x00000001001c469c miniruby`convert_type_with_id(val=4304780496, tname="String", method=3233, raise=0, index=-1) at object.c:3061:15
frame #32: 0x00000001001c4a4c miniruby`rb_check_convert_type_with_id(val=4304780496, type=5, tname="String", method=3233) at object.c:3153:9
frame #33: 0x00000001002d59f8 miniruby`rb_check_string_type(str=4304780496) at string.c:2571:11
frame #34: 0x000000010014b7b0 miniruby`io_encoding_set(fptr=0x0000000100d09ca0, v1=4304780496, v2=4, opt=4) at io.c:11655:19
frame #35: 0x0000000100139a58 miniruby`rb_io_set_encoding(argc=1, argv=0x000000016fdfb450, io=4308334032) at io.c:13497:5
frame #36: 0x00000001003c0004 miniruby`ractor_safe_call_cfunc_m1(recv=4308334032, argc=1, argv=0x000000016fdfb450, func=(miniruby`rb_io_set_encoding at io.c:13487)) at vm_insnhelper.c:3271:12
...
frame #43: 0x0000000100390b08 miniruby`rb_funcall(recv=4308334032, mid=16593, n=1) at vm_eval.c:1137:12
frame #44: 0x00000001002a43d8 miniruby`load_file_internal(argp_v=6171899936) at ruby.c:2500:5
...
```
wks
pushed a commit
that referenced
this pull request
Oct 16, 2023
to avoid deadlock
```ruby
r = Ractor.new do
obj = Thread.new{}
Ractor.yield obj
rescue => e
e.message
end
p r.take
```
```
(lldb) bt
* thread #1, name = 'miniruby', stop reason = signal SIGSTOP
* frame #0: 0x0000ffff44881410 libpthread.so.0`__lll_lock_wait + 88
frame #1: 0x0000ffff4487a078 libpthread.so.0`__pthread_mutex_lock + 232
frame #2: 0x0000aaab617c0980 miniruby`rb_native_mutex_lock(lock=<unavailable>) at thread_pthread.c:109:14
frame #3: 0x0000aaab617c1d58 miniruby`ubf_event_waiting [inlined] thread_sched_lock_(th=0x0000aaab9df82980, file=<unavailable>, line=46, sched=0x0000aaab9dec79b8) at thread_pthread.c:351:5
frame #4: 0x0000aaab617c1d50 miniruby`ubf_event_waiting(ptr=0x0000aaab9df82980) at thread_pthread_mn.c:46:5
frame #5: 0x0000aaab617c6020 miniruby`rb_threadptr_interrupt [inlined] rb_threadptr_interrupt_common(trap=0, th=0x0000aaab9df82980) at thread.c:352:25
frame #6: 0x0000aaab617c5fec miniruby`rb_threadptr_interrupt(th=0x0000aaab9df82980) at thread.c:365:5
frame #7: 0x0000aaab617379b0 miniruby`rb_ractor_terminate_all at ractor.c:2364:13
frame #8: 0x0000aaab6173797c miniruby`rb_ractor_terminate_all at ractor.c:2383:17
frame #9: 0x0000aaab61737958 miniruby`rb_ractor_terminate_all [inlined] ractor_terminal_interrupt_all(vm=0x0000aaab9dea3320) at ractor.c:2375:1
frame #10: 0x0000aaab61737950 miniruby`rb_ractor_terminate_all at ractor.c:2424:13
frame #11: 0x0000aaab6164f108 miniruby`rb_ec_cleanup(ec=0x0000aaab9dea5900, ex=RUBY_TAG_NONE) at eval.c:239:9
frame #12: 0x0000aaab6164fa3c miniruby`ruby_run_node(n=0x0000ffff417ed178) at eval.c:328:12
frame #13: 0x0000aaab615a5ab0 miniruby`main at main.c:39:12
frame #14: 0x0000aaab615a5a98 miniruby`main(argc=<unavailable>, argv=<unavailable>) at main.c:58:12
frame #15: 0x0000ffff44714b2c libc.so.6`__libc_start_main + 228
frame #16: 0x0000aaab615a5b0c miniruby`_start + 52
(lldb) thread select 3
* thread #3, name = 'bootstraptest.*', stop reason = signal SIGSTOP
frame #0: 0x0000ffff448813ec libpthread.so.0`__lll_lock_wait + 52
libpthread.so.0`__lll_lock_wait:
-> 0xffff448813ec <+52>: svc #0
0xffff448813f0 <+56>: eor w20, w20, #0x80
0xffff448813f4 <+60>: sxtw x20, w20
0xffff448813f8 <+64>: b 0xffff44881414 ; <+92>
(lldb) bt
* thread #3, name = 'bootstraptest.*', stop reason = signal SIGSTOP
* frame #0: 0x0000ffff448813ec libpthread.so.0`__lll_lock_wait + 52
frame #1: 0x0000ffff4487a078 libpthread.so.0`__pthread_mutex_lock + 232
frame #2: 0x0000aaab617c0980 miniruby`rb_native_mutex_lock(lock=<unavailable>) at thread_pthread.c:109:14
frame #3: 0x0000aaab61823d68 miniruby`rb_vm_lock_enter_body [inlined] vm_lock_enter(no_barrier=false, lev=0x0000ffff215bfbe4, locked=false, vm=0x0000aaab9dea3320, cr=0x0000aaab9dec7890) at vm_sync.c:57:9
frame #4: 0x0000aaab61823d60 miniruby`rb_vm_lock_enter_body(lev=0x0000ffff215bfbe4) at vm_sync.c:119:9
frame #5: 0x0000aaab617c1b30 miniruby`thread_sched_setup_running_threads [inlined] rb_vm_lock_enter(file=<unavailable>, line=597, lev=0x0000ffff215bfbe4) at vm_sync.h:75:9
frame #6: 0x0000aaab617c1b14 miniruby`thread_sched_setup_running_threads(vm=0x0000aaab9dea3320, add_th=0x0000aaab9df82980, del_th=<unavailable>, add_timeslice_th=0x0000000000000000, cr=<unavailable>, sched=<unavailable>, sched=<unavailable>) at thread_pthread.c:597:9
frame #7: 0x0000aaab617c29b4 miniruby`thread_sched_wait_running_turn at thread_pthread.c:614:5
frame #8: 0x0000aaab617c298c miniruby`thread_sched_wait_running_turn(sched=0x0000aaab9dec79b8, th=0x0000aaab9df82980, can_direct_transfer=true) at thread_pthread.c:868:9
frame #9: 0x0000aaab617c6f0c miniruby`thread_sched_wait_events(sched=0x0000aaab9dec79b8, th=0x0000aaab9df82980, fd=<unavailable>, events=<unavailable>, rel=<unavailable>) at thread_pthread_mn.c:90:17
frame #10: 0x0000aaab617c7354 miniruby`rb_thread_terminate_all at thread_pthread.c:3248:13
frame #11: 0x0000aaab617c733c miniruby`rb_thread_terminate_all(th=0x0000aaab9df82980) at thread.c:466:13
frame #12: 0x0000aaab617c7a64 miniruby`thread_start_func_2(th=0x0000aaab9df82980, stack_start=<unavailable>) at thread.c:713:9
frame #13: 0x0000aaab617c7d1c miniruby`co_start [inlined] call_thread_start_func_2(th=0x0000aaab9df82980) at thread_pthread.c:2165:5
frame #14: 0x0000aaab617c7cd0 miniruby`co_start(from=<unavailable>, self=0x0000aaab9df0f760) at thread_pthread_mn.c:421:9
```
peterzhu2118
added a commit
that referenced
this pull request
Aug 8, 2024
We're seeing a crash during shutdown in rb_gc_impl_objspace_free because
it's running lazy sweeping during shutdown. It appears that it's due to
`finalizing` being set, which causes GC to not be aborted and not
disabled which causes it to be in lazy sweeping at shutdown.
The full stack trace is:
#6 rb_bug (fmt=fmt@entry=0x5643b8ebde78 "lazy sweeping underway when freeing object space") at error.c:1095
#7 0x00005643b8a3c697 in rb_gc_impl_objspace_free (objspace_ptr=<optimized out>) at gc/default.c:9507
#8 0x00005643b8c269eb in ruby_vm_destruct (vm=0x7e2fdc84d000) at vm.c:3141
#9 0x00005643b8a5147b in rb_ec_cleanup (ec=<optimized out>, ex=<optimized out>) at eval.c:263
#10 0x00005643b8a51c93 in ruby_run_node (n=<optimized out>) at eval.c:319
#11 0x00005643b8a4c7c7 in rb_main (argv=0x7fffef15e7f8, argc=18) at ./main.c:43
#12 main (argc=<optimized out>, argv=<optimized out>) at ./main.c:62
peterzhu2118
added a commit
that referenced
this pull request
Oct 2, 2024
During compilation, we write keyword default values into the iseq, so we should mark it to ensure it does not get GC'd. This might fix issues on ASAN like http://ci.rvm.jp/logfiles/brlog.trunk_asan.20240927-194923 ==805257==ERROR: AddressSanitizer: use-after-poison on address 0x7b7e5e3e2828 at pc 0x5e09ac4822f8 bp 0x7ffde56b0140 sp 0x7ffde56b0138 READ of size 8 at 0x7b7e5e3e2828 thread T0 #0 0x5e09ac4822f7 in RB_BUILTIN_TYPE include/ruby/internal/value_type.h:191:30 #1 0x5e09ac4822f7 in rbimpl_RB_TYPE_P_fastpath include/ruby/internal/value_type.h:352:19 #2 0x5e09ac4822f7 in gc_mark gc/default.c:4488:9 #3 0x5e09ac51011e in rb_iseq_mark_and_move iseq.c:361:17 #4 0x5e09ac4b85c4 in rb_imemo_mark_and_move imemo.c:386:9 #5 0x5e09ac467544 in rb_gc_mark_children gc.c:2508:9 #6 0x5e09ac482c24 in gc_mark_children gc/default.c:4673:5 #7 0x5e09ac482c24 in gc_mark_stacked_objects gc/default.c:4694:9 #8 0x5e09ac482c24 in gc_mark_stacked_objects_all gc/default.c:4732:12 #9 0x5e09ac48c7f9 in gc_marks_rest gc/default.c:5755:9 #10 0x5e09ac48c7f9 in gc_marks gc/default.c:5870:9 #11 0x5e09ac48c7f9 in gc_start gc/default.c:6517:13
wks
pushed a commit
that referenced
this pull request
Dec 5, 2024
[Bug #20921]
When we create a cache entry for a constant, the following sequence of
events could happen:
- vm_track_constant_cache is called to insert a constant cache.
- In vm_track_constant_cache, we first look up the ST table for the ID
of the constant. Assume the ST table exists because another iseq also
holds a cache entry for this ID.
- We then insert into this ST table with the iseq_inline_constant_cache.
- However, while inserting into this ST table, it allocates memory, which
could trigger a GC. Assume that it does trigger a GC.
- The GC frees the one and only other iseq that holds a cache entry for
this ID.
- In remove_from_constant_cache, it will appear that the ST table is now
empty because there are no more iseq with cache entries for this ID, so
we free the ST table.
- We complete GC and continue our st_insert. However, this ST table has
been freed so we now have a use-after-free.
This issue is very hard to reproduce, because it requires that the GC runs
at a very specific time. However, we can make it show up by applying this
patch which runs GC right before the st_insert to mimic the st_insert
triggering a GC:
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 3cb23f0..a93998136a 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -6338,6 +6338,10 @@ vm_track_constant_cache(ID id, void *ic)
rb_id_table_insert(const_cache, id, (VALUE)ics);
}
+ if (id == rb_intern("MyConstant")) rb_gc();
+
st_insert(ics, (st_data_t) ic, (st_data_t) Qtrue);
}
And if we run this script:
Object.const_set("MyConstant", "Hello!")
my_proc = eval("-> { MyConstant }")
my_proc.call
my_proc = eval("-> { MyConstant }")
my_proc.call
We can see that ASAN outputs a use-after-free error:
==36540==ERROR: AddressSanitizer: heap-use-after-free on address 0x606000049528 at pc 0x000102f3ceac bp 0x00016d607a70 sp 0x00016d607a68
READ of size 8 at 0x606000049528 thread T0
#0 0x102f3cea8 in do_hash st.c:321
#1 0x102f3ddd0 in rb_st_insert st.c:1132
#2 0x103140700 in vm_track_constant_cache vm_insnhelper.c:6345
#3 0x1030b91d8 in vm_ic_track_const_chain vm_insnhelper.c:6356
#4 0x1030b8cf8 in rb_vm_opt_getconstant_path vm_insnhelper.c:6424
#5 0x1030bc1e0 in vm_exec_core insns.def:263
#6 0x1030b55fc in rb_vm_exec vm.c:2585
#7 0x1030fe0ac in rb_iseq_eval_main vm.c:2851
#8 0x102a82588 in rb_ec_exec_node eval.c:281
#9 0x102a81fe0 in ruby_run_node eval.c:319
#10 0x1027f3db4 in rb_main main.c:43
#11 0x1027f3bd4 in main main.c:68
#12 0x183900270 (<unknown module>)
0x606000049528 is located 8 bytes inside of 56-byte region [0x606000049520,0x606000049558)
freed by thread T0 here:
#0 0x104174d40 in free+0x98 (libclang_rt.asan_osx_dynamic.dylib:arm64e+0x54d40)
#1 0x102ada89c in rb_gc_impl_free default.c:8183
#2 0x102ada7dc in ruby_sized_xfree gc.c:4507
#3 0x102ac4d34 in ruby_xfree gc.c:4518
#4 0x102f3cb34 in rb_st_free_table st.c:663
#5 0x102bd52d8 in remove_from_constant_cache iseq.c:119
#6 0x102bbe2cc in iseq_clear_ic_references iseq.c:153
#7 0x102bbd2a0 in rb_iseq_free iseq.c:166
#8 0x102b32ed0 in rb_imemo_free imemo.c:564
#9 0x102ac4b44 in rb_gc_obj_free gc.c:1407
#10 0x102af4290 in gc_sweep_plane default.c:3546
#11 0x102af3bdc in gc_sweep_page default.c:3634
#12 0x102aeb140 in gc_sweep_step default.c:3906
#13 0x102aeadf0 in gc_sweep_rest default.c:3978
#14 0x102ae4714 in gc_sweep default.c:4155
#15 0x102af8474 in gc_start default.c:6484
#16 0x102afbe30 in garbage_collect default.c:6363
#17 0x102ad37f0 in rb_gc_impl_start default.c:6816
#18 0x102ad3634 in rb_gc gc.c:3624
#19 0x1031406ec in vm_track_constant_cache vm_insnhelper.c:6342
#20 0x1030b91d8 in vm_ic_track_const_chain vm_insnhelper.c:6356
#21 0x1030b8cf8 in rb_vm_opt_getconstant_path vm_insnhelper.c:6424
#22 0x1030bc1e0 in vm_exec_core insns.def:263
#23 0x1030b55fc in rb_vm_exec vm.c:2585
#24 0x1030fe0ac in rb_iseq_eval_main vm.c:2851
#25 0x102a82588 in rb_ec_exec_node eval.c:281
#26 0x102a81fe0 in ruby_run_node eval.c:319
#27 0x1027f3db4 in rb_main main.c:43
#28 0x1027f3bd4 in main main.c:68
#29 0x183900270 (<unknown module>)
previously allocated by thread T0 here:
#0 0x104174c04 in malloc+0x94 (libclang_rt.asan_osx_dynamic.dylib:arm64e+0x54c04)
#1 0x102ada0ec in rb_gc_impl_malloc default.c:8198
#2 0x102acee44 in ruby_xmalloc gc.c:4438
#3 0x102f3c85c in rb_st_init_table_with_size st.c:571
#4 0x102f3c900 in rb_st_init_table st.c:600
#5 0x102f3c920 in rb_st_init_numtable st.c:608
#6 0x103140698 in vm_track_constant_cache vm_insnhelper.c:6337
#7 0x1030b91d8 in vm_ic_track_const_chain vm_insnhelper.c:6356
#8 0x1030b8cf8 in rb_vm_opt_getconstant_path vm_insnhelper.c:6424
#9 0x1030bc1e0 in vm_exec_core insns.def:263
#10 0x1030b55fc in rb_vm_exec vm.c:2585
#11 0x1030fe0ac in rb_iseq_eval_main vm.c:2851
#12 0x102a82588 in rb_ec_exec_node eval.c:281
#13 0x102a81fe0 in ruby_run_node eval.c:319
#14 0x1027f3db4 in rb_main main.c:43
#15 0x1027f3bd4 in main main.c:68
#16 0x183900270 (<unknown module>)
This commit fixes this bug by adding a inserting_constant_cache_id field
to the VM, which stores the ID that is currently being inserted and, in
remove_from_constant_cache, we don't free the ST table for ID equal to
this one.
Co-Authored-By: Alan Wu <[email protected]>
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This PR is a work in progress.
I've added a flag
RUBY_TYPED_DECL_MARKINGthat can be used inside therb_data_type_tflags section to determine whether a T_DATA object can be declaratively marked or not.If this flag is set then we can use the
datastruct member as a pointer to an array of offsets that we can use in conjunction with thedatastruct to find fields that require marking.I've modified
gc_mark_childrento use this offset array if present to test the system.