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Basic GC.stat for MMTk #4
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It decreased, but you filtered out all fields with
I slightly changed the number of iterations to make it run faster. My program runs for one million iterations, so it effectively creates two million three-element arrays. Assume each three-element array fits in a 40-byte slot, and my mmtk-ruby binding adds one 8-byte hidden field to record the object size. It should be a total of 96MB of allocation, which is pretty close to -117276672, assuming that there are other objects created during the execution, or there is overhead for the underlying If I set |
Since the code is actually working, I merged this PR. |
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]
[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 ... ```
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 ```
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
fill_lines is passed -1 for offset, which causes it to read the -1 index of traces. This is not valid memory as -1 is reading before the trace global variable in rb_print_backtrace. This code comes from commit 99d1f5f, where there used to be special handling for the -1 index. We can see this error in ASAN: ==71037==ERROR: AddressSanitizer: global-buffer-overflow on address 0x00010157abf8 at pc 0x00010116f3b8 bp 0x00016f92c3b0 sp 0x00016f92c3a8 READ of size 8 at 0x00010157abf8 thread T0 #0 0x10116f3b4 in debug_info_read addr2line.c:1945 #1 0x10116cc90 in fill_lines addr2line.c:2497 #2 0x101169dbc in rb_dump_backtrace_with_lines addr2line.c:2635 #3 0x100e56788 in rb_print_backtrace vm_dump.c:825 #4 0x100e56db4 in rb_vm_bugreport vm_dump.c:1155 #5 0x100734dc4 in rb_bug_without_die error.c:1085 #6 0x100734ae4 in rb_bug error.c:109
[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]>
When searching for native extensions, if the name does not end in ".so" then we create a new string and append ".so" so it. If the native extension is in static_ext_inits, then we could trigger a GC in the rb_filesystem_str_new_cstr. This could cuase the GC to free lookup_name since we don't use the local variable anymore. This bug was caught in this ASAN build: http://ci.rvm.jp/results/trunk_asan@ruby-sp1/5479182 ==435614==ERROR: AddressSanitizer: use-after-poison on address 0x715a63022da0 at pc 0x5e7463873e4e bp 0x7fff383c8b00 sp 0x7fff383c82c0 READ of size 14 at 0x715a63022da0 thread T0 #0 0x5e7463873e4d in __asan_memcpy (/tmp/ruby/build/trunk_asan/ruby+0x214e4d) (BuildId: 607411c0626a2f66b4c20c02179b346aace20898) #1 0x5e7463b50a82 in memcpy /usr/include/x86_64-linux-gnu/bits/string_fortified.h:29:10 #2 0x5e7463b50a82 in ruby_nonempty_memcpy /tmp/ruby/src/trunk_asan/include/ruby/internal/memory.h:671:16 #3 0x5e7463b50a82 in str_enc_new /tmp/ruby/src/trunk_asan/string.c:1035:9 #4 0x5e74639b97dd in search_required /tmp/ruby/src/trunk_asan/load.c:1126:21 #5 0x5e74639b97dd in require_internal /tmp/ruby/src/trunk_asan/load.c:1274:17 #6 0x5e74639b83c1 in rb_require_string_internal /tmp/ruby/src/trunk_asan/load.c:1401:22 #7 0x5e74639b83c1 in rb_require_string /tmp/ruby/src/trunk_asan/load.c:1387:12
…uby#13231) This change addresses the following ASAN error: ``` ==36597==ERROR: AddressSanitizer: heap-use-after-free on address 0x512000396ba8 at pc 0x7fcad5cbad9f bp 0x7fff19739af0 sp 0x7fff19739ae8 WRITE of size 8 at 0x512000396ba8 thread T0 [643/756] 36600=optparse/test_summary #0 0x7fcad5cbad9e in free_fast_fallback_getaddrinfo_entry /home/runner/work/ruby-dev-builder/ruby-dev-builder/ext/socket/raddrinfo.c:3046:22 #1 0x7fcad5c9fb48 in fast_fallback_inetsock_cleanup /home/runner/work/ruby-dev-builder/ruby-dev-builder/ext/socket/ipsocket.c:1179:17 #2 0x7fcadf3b611a in rb_ensure /home/runner/work/ruby-dev-builder/ruby-dev-builder/eval.c:1081:5 #3 0x7fcad5c9b44b in rsock_init_inetsock /home/runner/work/ruby-dev-builder/ruby-dev-builder/ext/socket/ipsocket.c:1289:20 #4 0x7fcad5ca22b8 in tcp_init /home/runner/work/ruby-dev-builder/ruby-dev-builder/ext/socket/tcpsocket.c:76:12 #5 0x7fcadf83ba70 in vm_call0_cfunc_with_frame /home/runner/work/ruby-dev-builder/ruby-dev-builder/./vm_eval.c:164:15 ... ``` A `struct fast_fallback_getaddrinfo_shared` is shared between the main thread and two child threads. This struct contains an array of `fast_fallback_getaddrinfo_entry`. `fast_fallback_getaddrinfo_entry` and `fast_fallback_getaddrinfo_shared` were freed separately, and if `fast_fallback_getaddrinfo_shared` was freed first and then an attempt was made to free a `fast_fallback_getaddrinfo_entry`, a `heap-use-after-free` could occur. This change avoids that possibility by separating the deallocation of the addrinfo memory held by `fast_fallback_getaddrinfo_entry` from the access and lifecycle of the `fast_fallback_getaddrinfo_entry` itself.
[Bug #18119] When we create classes, it pushes the class to the subclass list of the superclass. This access needs to be synchronized because multiple Ractors may be creating classes with the same superclass, which would cause race conditions and cause the linked list to be corrupted. For example, we can reproduce with this script crashing: workers = (0...8).map do Ractor.new do loop do 100.times.map { Class.new } Ractor.yield nil end end end 100.times { Ractor.select(*workers) } With ASAN enabled, we can see that there are use-after-free errors: ==176013==ERROR: AddressSanitizer: heap-use-after-free on address 0x5030000974f0 at pc 0x62f9e56f892d bp 0x7a503f1ffd90 sp 0x7a503f1ffd88 WRITE of size 8 at 0x5030000974f0 thread T4 #0 0x62f9e56f892c in rb_class_remove_from_super_subclasses class.c:149:24 #1 0x62f9e58c9dd2 in rb_gc_obj_free gc.c:1262:9 #2 0x62f9e58f6e19 in gc_sweep_plane gc/default/default.c:3450:21 #3 0x62f9e58f686a in gc_sweep_page gc/default/default.c:3535:13 #4 0x62f9e58f12b4 in gc_sweep_step gc/default/default.c:3810:9 #5 0x62f9e58ed2a7 in gc_sweep gc/default/default.c:4058:13 #6 0x62f9e58fac93 in gc_start gc/default/default.c:6402:13 #7 0x62f9e58e8b69 in heap_prepare gc/default/default.c:2032:13 #8 0x62f9e58e8b69 in heap_next_free_page gc/default/default.c:2255:9 #9 0x62f9e58e8b69 in newobj_cache_miss gc/default/default.c:2362:38 ... 0x5030000974f0 is located 16 bytes inside of 24-byte region [0x5030000974e0,0x5030000974f8) freed by thread T4 here: #0 0x62f9e562f28a in free (miniruby+0x1fd28a) (BuildId: 5ad6d9e7cec8318df6726ea5ce34d3c76d0d0233) #1 0x62f9e58ca2ab in rb_gc_impl_free gc/default/default.c:8102:9 #2 0x62f9e58ca2ab in ruby_sized_xfree gc.c:5029:13 #3 0x62f9e58ca2ab in ruby_xfree gc.c:5040:5 #4 0x62f9e56f88e6 in rb_class_remove_from_super_subclasses class.c:152:9 #5 0x62f9e58c9dd2 in rb_gc_obj_free gc.c:1262:9 #6 0x62f9e58f6e19 in gc_sweep_plane gc/default/default.c:3450:21 #7 0x62f9e58f686a in gc_sweep_page gc/default/default.c:3535:13 #8 0x62f9e58f12b4 in gc_sweep_step gc/default/default.c:3810:9 #9 0x62f9e58ed2a7 in gc_sweep gc/default/default.c:4058:13 ... previously allocated by thread T5 here: #0 0x62f9e562f70d in calloc (miniruby+0x1fd70d) (BuildId: 5ad6d9e7cec8318df6726ea5ce34d3c76d0d0233) #1 0x62f9e58c8e1a in calloc1 gc/default/default.c:1472:12 #2 0x62f9e58c8e1a in rb_gc_impl_calloc gc/default/default.c:8138:5 #3 0x62f9e58c8e1a in ruby_xcalloc_body gc.c:4964:12 #4 0x62f9e58c8e1a in ruby_xcalloc gc.c:4958:34 #5 0x62f9e56f906e in push_subclass_entry_to_list class.c:88:13 #6 0x62f9e56f906e in rb_class_subclass_add class.c:111:38 #7 0x62f9e56f906e in RCLASS_SET_SUPER internal/class.h:257:9 #8 0x62f9e56fca7a in make_metaclass class.c:786:5 #9 0x62f9e59db982 in rb_class_initialize object.c:2101:5
Fix towards mmtk/mmtk-ruby#1.
Is
mmtk_free_bytes
working? Why doesn't it change with allocation and collection activity?