introduce LinearTable v2 for small hash #5

yimin-zhao · 2018-07-29T09:34:27Z

Signed-off-by: tacinight [email protected]

Signed-off-by: tacinight <[email protected]>

Hash#merge, merge!, and update could merge exactly two hashes. Now, they accepts zero or more hashes as arguments so that it can merge hashes more than two. This patch was created by Koki Ryu <[email protected]> at Ruby Hack Challenge #5. Thank you! [ruby-core:88970] [Feature #15111] [Fix rubyGH-1951] git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64777 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

This funcion can be called from inside of rb_ast_new(). Should add appropriate case branches. (lldb) run Process 9135 launched: './miniruby' (x86_64) Process 9135 stopped * thread #1: tid = 0xdf36b, 0x00000001000ca4f9 miniruby`rb_raw_obj_info(buff="0x000000010205d158 [0 ] T_IMEMO", buff_size=256, obj=4328903000) + 2361 at gc.c:9617, queue = 'com.apple.main-thread', stop reason = EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0) frame #0: 0x00000001000ca4f9 miniruby`rb_raw_obj_info(buff="0x000000010205d158 [0 ] T_IMEMO", buff_size=256, obj=4328903000) + 2361 at gc.c:9617 9614 IMEMO_NAME(iseq); 9615 IMEMO_NAME(tmpbuf); 9616 #undef IMEMO_NAME -> 9617 default: UNREACHABLE; 9618 } 9619 snprintf(buff, buff_size, "%s %s", buff, imemo_name); 9620 (lldb) bt * thread #1: tid = 0xdf36b, 0x00000001000ca4f9 miniruby`rb_raw_obj_info(buff="0x000000010205d158 [0 ] T_IMEMO", buff_size=256, obj=4328903000) + 2361 at gc.c:9617, queue = 'com.apple.main-thread', stop reason = EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0) * frame #0: 0x00000001000ca4f9 miniruby`rb_raw_obj_info(buff="0x000000010205d158 [0 ] T_IMEMO", buff_size=256, obj=4328903000) + 2361 at gc.c:9617 frame #1: 0x00000001000c433f miniruby`obj_info(obj=4328903000) + 95 at gc.c:9671 frame #2: 0x00000001000ce2ac miniruby`newobj_init(klass=4302478608, flags=36890, v1=0, v2=0, v3=0, wb_protected=1, objspace=0x0000000101800410, obj=4328903000) + 444 at gc.c:1882 frame #3: 0x00000001000c0a49 miniruby`newobj_of(klass=4302478608, flags=36890, v1=0, v2=0, v3=0, wb_protected=1) + 217 at gc.c:1968 frame #4: 0x00000001000c0bcb miniruby`rb_imemo_new(type=imemo_ast, v1=0, v2=0, v3=0, v0=4302478608) + 75 at gc.c:2017 frame #5: 0x0000000100148f2a miniruby`rb_ast_new + 58 at node.c:1118 frame #6: 0x000000010018d9e2 miniruby`yycompile(vparser=4328903720, p=0x0000000100729670, fname=4328903160, line=1) + 98 at parse.y:4925 frame #7: 0x000000010018d66f miniruby`parser_compile_string(vparser=4328903720, fname=4328903160, s=4328904440, line=1) + 143 at parse.y:4995 frame #8: 0x000000010018d768 miniruby`rb_parser_compile_string_path(vparser=4328903720, f=4328903160, s=4328904440, line=1) + 56 at parse.y:5015 frame #9: 0x000000010018d71e miniruby`rb_parser_compile_string(vparser=4328903720, f="-e", s=4328904440, line=1) + 62 at parse.y:5008 frame #10: 0x00000001002130d5 miniruby`process_options(argc=0, argv=0x00007fff5fbfdc08, opt=0x00007fff5fbfd9e8) + 3477 at ruby.c:1754 frame #11: 0x00000001002122dd miniruby`ruby_process_options(argc=2, argv=0x00007fff5fbfdbf8) + 285 at ruby.c:2332 frame #12: 0x00000001000aa966 miniruby`ruby_options(argc=2, argv=0x00007fff5fbfdbf8) + 262 at eval.c:118 frame #13: 0x0000000100000ed4 miniruby`main(argc=2, argv=0x00007fff5fbfdbf8) + 116 at main.c:42 frame #14: 0x00007fff933845ad libdyld.dylib`start + 1 frame #15: 0x00007fff933845ad libdyld.dylib`start + 1 (lldb) git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65148 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

This is rather nitpicking but at the moment the process terminates, heap_pages_final_slots overflows. (lldb) bt * thread #1: tid = 0xc0903, 0x00000001002b3bf7 miniruby`finalize_list(objspace=0x0000000101c09240, zombie=4329149840) + 999 at gc.c:2946, queue = 'com.apple.main-thread', stop reason = EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0) * frame #0: 0x00000001002b3bf7 miniruby`finalize_list(objspace=0x0000000101c09240, zombie=4329149840) + 999 at gc.c:2946 frame #1: 0x000000010026a69e miniruby`rb_objspace_call_finalizer(objspace=0x0000000101c09240) + 7118 at gc.c:3092 frame #2: 0x0000000100268ac5 miniruby`rb_gc_call_finalizer_at_exit + 149 at gc.c:3015 frame #3: 0x00000001002272bc miniruby`ruby_finalize_1 + 156 at eval.c:146 frame #4: 0x00000001002282b6 miniruby`ruby_cleanup(ex=0) + 4070 at eval.c:238 frame #5: 0x0000000100228785 miniruby`ruby_run_node(n=0x0000000102060ad8) + 85 at eval.c:317 frame #6: 0x0000000100000b9c miniruby`main(argc=2, argv=0x00007fff5fbfdc38) + 124 at main.c:42 frame #7: 0x00007fff9966a5ad libdyld.dylib`start + 1 frame #8: 0x00007fff9966a5ad libdyld.dylib`start + 1 (lldb) p objspace->heap_pages (rb_objspace::(anonymous struct)) $0 = { sorted = 0x0000000101c070b0 allocated_pages = 24 allocatable_pages = 0 sorted_length = 24 range = { [0] = 0x0000000102020028 [1] = 0x00000001020dbfd0 } freeable_pages = 0 final_slots = 0 deferred_final = 4329149840 } (lldb) git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65633 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

memo.float_value might change inside of hash_sum. In case it flipped from false to true there, and the calculated sum is Inf, memo.c might not be initialized at all. This is bad. Found using memory sanitizer: ==55293==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x55dfb8d6c529 in rb_float_new_inline internal.h:1814:53 #1 0x55dfb8d1b30c in enum_sum enum.c:4017:18 #2 0x55dfb86d75ad in call_cfunc_m1 vm_insnhelper.c:2041:12 #3 0x55dfb864b141 in vm_call_cfunc_with_frame vm_insnhelper.c:2207:11 #4 0x55dfb85e843d in vm_call_cfunc vm_insnhelper.c:2225:12 #5 0x55dfb85e08f3 in vm_call_method_each_type vm_insnhelper.c:2560:9 #6 0x55dfb85de9c7 in vm_call_method vm_insnhelper.c:2686:13 #7 0x55dfb849eac6 in vm_call_general vm_insnhelper.c:2730:12 #8 0x55dfb8686103 in vm_sendish vm_insnhelper.c:3623:11 #9 0x55dfb84dc29e in vm_exec_core insns.def:789:11

ec->cfp->iseq might not exist at the very beginning of a thread. ================================================================= ==82954==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x7fc86f334810 at pc 0x55ceaf013125 bp 0x7ffe2eddbbf0 sp 0x7ffe2eddbbe8 READ of size 8 at 0x7fc86f334810 thread T0 #0 0x55ceaf013124 in vm_check_canary vm_insnhelper.c:217:24 #1 0x55ceaefb4796 in vm_push_frame vm_insnhelper.c:276:5 #2 0x55ceaf0124bd in th_init vm.c:2661:5 #3 0x55ceaf00d5eb in ruby_thread_init vm.c:2690:5 #4 0x55ceaf00d4b1 in rb_thread_alloc vm.c:2703:5 #5 0x55ceaef0038b in thread_s_new thread.c:872:20 #6 0x55ceaf04d8c1 in call_cfunc_m1 vm_insnhelper.c:2041:12 #7 0x55ceaf03118d in vm_call_cfunc_with_frame vm_insnhelper.c:2207:11 #8 0x55ceaf017985 in vm_call_cfunc vm_insnhelper.c:2225:12 #9 0x55ceaf01548b in vm_call_method_each_type vm_insnhelper.c:2560:9 #10 0x55ceaf014c96 in vm_call_method vm_insnhelper.c:2686:13 #11 0x55ceaefb5de4 in vm_call_general vm_insnhelper.c:2730:12 #12 0x55ceaf03c868 in vm_sendish vm_insnhelper.c:3623:11 #13 0x55ceaefc95bb in vm_exec_core insns.def:771:11 #14 0x55ceaf006700 in rb_vm_exec vm.c:1892:22 #15 0x55ceaf00acbf in rb_iseq_eval_main vm.c:2151:11 #16 0x55ceaea250ca in ruby_exec_internal eval.c:262:2 ruby#17 0x55ceaea2498b in ruby_exec_node eval.c:326:12 ruby#18 0x55ceaea247d0 in ruby_run_node eval.c:318:25 ruby#19 0x55ceae88c486 in main main.c:42:9 #20 0x7fc874330b96 in __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:310 ruby#21 0x55ceae7e5289 in _start (miniruby+0x15f289) 0x7fc86f334810 is located 16 bytes to the right of 1048576-byte region [0x7fc86f234800,0x7fc86f334800) allocated by thread T0 here: #0 0x55ceae85d56d in malloc (miniruby+0x1d756d) #1 0x55ceaea71d12 in objspace_xmalloc0 gc.c:9416:5 #2 0x55ceaea71cd2 in ruby_xmalloc2_body gc.c:9623:12 #3 0x55ceaea7d09c in ruby_xmalloc2 gc.c:11479:12 #4 0x55ceaf00c3b7 in rb_thread_recycle_stack vm.c:2462:12 #5 0x55ceaf012256 in th_init vm.c:2656:29 #6 0x55ceaf00d5eb in ruby_thread_init vm.c:2690:5 #7 0x55ceaf00d4b1 in rb_thread_alloc vm.c:2703:5 #8 0x55ceaef0038b in thread_s_new thread.c:872:20 #9 0x55ceaf04d8c1 in call_cfunc_m1 vm_insnhelper.c:2041:12 #10 0x55ceaf03118d in vm_call_cfunc_with_frame vm_insnhelper.c:2207:11 #11 0x55ceaf017985 in vm_call_cfunc vm_insnhelper.c:2225:12 #12 0x55ceaf01548b in vm_call_method_each_type vm_insnhelper.c:2560:9 #13 0x55ceaf014c96 in vm_call_method vm_insnhelper.c:2686:13 #14 0x55ceaefb5de4 in vm_call_general vm_insnhelper.c:2730:12 #15 0x55ceaf03c868 in vm_sendish vm_insnhelper.c:3623:11 #16 0x55ceaefc95bb in vm_exec_core insns.def:771:11 ruby#17 0x55ceaf006700 in rb_vm_exec vm.c:1892:22 ruby#18 0x55ceaf00acbf in rb_iseq_eval_main vm.c:2151:11 ruby#19 0x55ceaea250ca in ruby_exec_internal eval.c:262:2 #20 0x55ceaea2498b in ruby_exec_node eval.c:326:12 ruby#21 0x55ceaea247d0 in ruby_run_node eval.c:318:25 ruby#22 0x55ceae88c486 in main main.c:42:9 ruby#23 0x7fc874330b96 in __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:310 SUMMARY: AddressSanitizer: heap-buffer-overflow vm_insnhelper.c:217:24 in vm_check_canary Shadow bytes around the buggy address: 0x0ff98de5e8b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0ff98de5e8c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0ff98de5e8d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0ff98de5e8e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0ff98de5e8f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 =>0x0ff98de5e900: fa fa[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0ff98de5e910: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0ff98de5e920: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0ff98de5e930: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0ff98de5e940: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0ff98de5e950: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa Shadow byte legend (one shadow byte represents 8 application bytes): Addressable: 00 Partially addressable: 01 02 03 04 05 06 07 Heap left redzone: fa Freed heap region: fd Stack left redzone: f1 Stack mid redzone: f2 Stack right redzone: f3 Stack after return: f5 Stack use after scope: f8 Global redzone: f9 Global init order: f6 Poisoned by user: f7 Container overflow: fc Array cookie: ac Intra object redzone: bb ASan internal: fe Left alloca redzone: ca Right alloca redzone: cb Shadow gap: cc ==82954==ABORTING

rb_io_fptr_finalize_internal frees the memory region. ================================================================= ==85264==ERROR: AddressSanitizer: heap-use-after-free on address 0x610000000d8c at pc 0x5608e38077f7 bp 0x7ffee12d5440 sp 0x7ffee12d5438 READ of size 4 at 0x610000000d8c thread T0 #0 0x5608e38077f6 in rb_io_memsize io.c:4749:24 #1 0x5608e37a0481 in obj_memsize_of gc.c:3547:14 #2 0x5608e37a4f30 in check_rvalue_consistency gc.c:1107:2 #3 0x5608e37a2624 in RVALUE_OLD_P gc.c:1218:5 #4 0x5608e37a5bae in rb_gc_force_recycle gc.c:6652:18 #5 0x5608e38191f9 in rb_f_backquote io.c:9021:5 #6 0x5608e3d8aa14 in call_cfunc_1 vm_insnhelper.c:2058:12 #7 0x5608e3d6e23d in vm_call_cfunc_with_frame vm_insnhelper.c:2211:11 #8 0x5608e3d54a35 in vm_call_cfunc vm_insnhelper.c:2229:12 #9 0x5608e3d5253b in vm_call_method_each_type vm_insnhelper.c:2564:9 #10 0x5608e3d51f50 in vm_call_method vm_insnhelper.c:2701:13 #11 0x5608e3cf2de4 in vm_call_general vm_insnhelper.c:2734:12 #12 0x5608e3d79918 in vm_sendish vm_insnhelper.c:3627:11 #13 0x5608e3d06cf5 in vm_exec_core insns.def:789:11 #14 0x5608e3d43700 in rb_vm_exec vm.c:1892:22 #15 0x5608e3d47cbf in rb_iseq_eval_main vm.c:2151:11 #16 0x5608e37620ca in ruby_exec_internal eval.c:262:2 ruby#17 0x5608e376198b in ruby_exec_node eval.c:326:12 ruby#18 0x5608e37617d0 in ruby_run_node eval.c:318:25 ruby#19 0x5608e35c9486 in main main.c:42:9 #20 0x7f62e9421b96 in __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:310 ruby#21 0x5608e3522289 in _start (miniruby+0x15f289) 0x610000000d8c is located 76 bytes inside of 192-byte region [0x610000000d40,0x610000000e00) freed by thread T0 here: #0 0x5608e359a2ed in free (miniruby+0x1d72ed) #1 0x5608e37af421 in objspace_xfree gc.c:9591:5 #2 0x5608e37af3da in ruby_sized_xfree gc.c:9687:2 #3 0x5608e3799ac8 in ruby_xfree gc.c:9694:5 #4 0x5608e380746d in rb_io_fptr_finalize_internal io.c:4728:5 #5 0x5608e38191ed in rb_f_backquote io.c:9020:5 #6 0x5608e3d8aa14 in call_cfunc_1 vm_insnhelper.c:2058:12 #7 0x5608e3d6e23d in vm_call_cfunc_with_frame vm_insnhelper.c:2211:11 #8 0x5608e3d54a35 in vm_call_cfunc vm_insnhelper.c:2229:12 #9 0x5608e3d5253b in vm_call_method_each_type vm_insnhelper.c:2564:9 #10 0x5608e3d51f50 in vm_call_method vm_insnhelper.c:2701:13 #11 0x5608e3cf2de4 in vm_call_general vm_insnhelper.c:2734:12 #12 0x5608e3d79918 in vm_sendish vm_insnhelper.c:3627:11 #13 0x5608e3d06cf5 in vm_exec_core insns.def:789:11 #14 0x5608e3d43700 in rb_vm_exec vm.c:1892:22 #15 0x5608e3d47cbf in rb_iseq_eval_main vm.c:2151:11 #16 0x5608e37620ca in ruby_exec_internal eval.c:262:2 ruby#17 0x5608e376198b in ruby_exec_node eval.c:326:12 ruby#18 0x5608e37617d0 in ruby_run_node eval.c:318:25 ruby#19 0x5608e35c9486 in main main.c:42:9 #20 0x7f62e9421b96 in __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:310 previously allocated by thread T0 here: #0 0x5608e359a56d in malloc (miniruby+0x1d756d) #1 0x5608e37aed12 in objspace_xmalloc0 gc.c:9416:5 #2 0x5608e37aebe7 in ruby_xmalloc0 gc.c:9600:12 #3 0x5608e37aea8b in ruby_xmalloc_body gc.c:9609:12 #4 0x5608e37a6d64 in ruby_xmalloc gc.c:11469:12 #5 0x5608e380e4b4 in rb_io_fptr_new io.c:8040:19 #6 0x5608e380e446 in rb_io_make_open_file io.c:8077:10 #7 0x5608e3850ea0 in pipe_open io.c:6707:5 #8 0x5608e384edb4 in pipe_open_s io.c:6772:12 #9 0x5608e381910b in rb_f_backquote io.c:9014:12 #10 0x5608e3d8aa14 in call_cfunc_1 vm_insnhelper.c:2058:12 #11 0x5608e3d6e23d in vm_call_cfunc_with_frame vm_insnhelper.c:2211:11 #12 0x5608e3d54a35 in vm_call_cfunc vm_insnhelper.c:2229:12 #13 0x5608e3d5253b in vm_call_method_each_type vm_insnhelper.c:2564:9 #14 0x5608e3d51f50 in vm_call_method vm_insnhelper.c:2701:13 #15 0x5608e3cf2de4 in vm_call_general vm_insnhelper.c:2734:12 #16 0x5608e3d79918 in vm_sendish vm_insnhelper.c:3627:11 ruby#17 0x5608e3d06cf5 in vm_exec_core insns.def:789:11 ruby#18 0x5608e3d43700 in rb_vm_exec vm.c:1892:22 ruby#19 0x5608e3d47cbf in rb_iseq_eval_main vm.c:2151:11 #20 0x5608e37620ca in ruby_exec_internal eval.c:262:2 ruby#21 0x5608e376198b in ruby_exec_node eval.c:326:12 ruby#22 0x5608e37617d0 in ruby_run_node eval.c:318:25 ruby#23 0x5608e35c9486 in main main.c:42:9 ruby#24 0x7f62e9421b96 in __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:310 SUMMARY: AddressSanitizer: heap-use-after-free io.c:4749:24 in rb_io_memsize Shadow bytes around the buggy address: 0x0c207fff8160: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00 0x0c207fff8170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c207fff8180: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00 0x0c207fff8190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c207fff81a0: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd =>0x0c207fff81b0: fd[fd]fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x0c207fff81c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c207fff81d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c207fff81e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c207fff81f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c207fff8200: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa Shadow byte legend (one shadow byte represents 8 application bytes): Addressable: 00 Partially addressable: 01 02 03 04 05 06 07 Heap left redzone: fa Freed heap region: fd Stack left redzone: f1 Stack mid redzone: f2 Stack right redzone: f3 Stack after return: f5 Stack use after scope: f8 Global redzone: f9 Global init order: f6 Poisoned by user: f7 Container overflow: fc Array cookie: ac Intra object redzone: bb ASan internal: fe Left alloca redzone: ca Right alloca redzone: cb Shadow gap: cc ==85264==ABORTING

This changeset makes no difference unless GC_DEBUG is on. When that flag is set, struct RVALUE is bigger than struct RObject. We have to take care of the additional fields. Otherwise we get a SIGSEGV like shown below. The way obj is initialized in this patch works for both GC_DEBUG is on and off. See also ISO/IEC 9899:1999 section 6.7.8 paragraph ruby#21. ``` Program received signal SIGSEGV, Segmentation fault. __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:62 62 ../sysdeps/x86_64/multiarch/strlen-avx2.S: No such file or directory (gdb) bt #0 __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:62 #1 0x00005555557dd9a7 in BSD_vfprintf (fp=0x7fffffff6be0, fmt0=0x5555558f3059 "@%s:%d", ap=0x7fffffff6dd0) at vsnprintf.c:1027 #2 0x00005555557db6f5 in ruby_do_vsnprintf (str=0x555555bfc58d <obj_info_buffers+1325> "", n=211, fmt=0x5555558f3059 "@%s:%d", ap=0x7fffffff6dd0) at sprintf.c:1022 #3 0x00005555557db909 in ruby_snprintf (str=0x555555bfc58d <obj_info_buffers+1325> "", n=211, fmt=0x5555558f3059 "@%s:%d") at sprintf.c:1040 #4 0x0000555555661ef4 in rb_raw_obj_info (buff=0x555555bfc560 <obj_info_buffers+1280> "0x0000555555d2bfa0 [0 ] T_STRING (String)", buff_size=256, obj=93825000456096) at gc.c:11449 #5 0x000055555565baaf in obj_info (obj=93825000456096) at gc.c:11612 #6 0x000055555565bae1 in rgengc_remembered (objspace=0x555555c0a1c0, obj=93825000456096) at gc.c:6618 #7 0x0000555555666987 in newobj_init (klass=93824999964192, flags=5, v1=0, v2=0, v3=0, wb_protected=1, objspace=0x555555c0a1c0, obj=93825000456096) at gc.c:2134 #8 0x0000555555666e49 in newobj_slowpath (klass=93824999964192, flags=5, v1=0, v2=0, v3=0, objspace=0x555555c0a1c0, wb_protected=1) at gc.c:2209 #9 0x0000555555666b94 in newobj_slowpath_wb_protected (klass=93824999964192, flags=5, v1=0, v2=0, v3=0, objspace=0x555555c0a1c0) at gc.c:2220 #10 0x000055555565751b in newobj_of (klass=93824999964192, flags=5, v1=0, v2=0, v3=0, wb_protected=1) at gc.c:2256 #11 0x00005555556575ca in rb_wb_protected_newobj_of (klass=93824999964192, flags=5) at gc.c:2272 #12 0x00005555557f36ea in str_alloc (klass=93824999964192) at string.c:728 #13 0x00005555557f2128 in rb_str_buf_new (capa=0) at string.c:1317 #14 0x000055555578c66d in rb_reg_preprocess (p=0x555555cc8148 "^-(.)(.+)?", end=0x555555cc8152 "", enc=0x555555cc7c80, fixed_enc=0x7fffffff74e8, err=0x7fffffff75f0 "") at re.c:2682 #15 0x000055555578ea13 in rb_reg_initialize (obj=93825000046736, s=0x555555cc8148 "^-(.)(.+)?", len=10, enc=0x555555cc7c80, options=0, err=0x7fffffff75f0 "", sourcefile=0x555555d1a5c0 "lib/optparse.rb", sourceline=1460) at re.c:2808 #16 0x000055555578e285 in rb_reg_initialize_str (obj=93825000046736, str=93825000046904, options=0, err=0x7fffffff75f0 "", sourcefile=0x555555d1a5c0 "lib/optparse.rb", sourceline=1460) at re.c:2869 ruby#17 0x000055555578ee02 in rb_reg_compile (str=93825000046904, options=0, sourcefile=0x555555d1a5c0 "lib/optparse.rb", sourceline=1460) at re.c:2958 ruby#18 0x0000555555748dfb in rb_parser_reg_compile (p=0x555555d1f760, str=93825000046904, options=0) at parse.y:12157 ruby#19 0x00005555557581c3 in parser_reg_compile (p=0x555555d1f760, str=93825000046904, options=0) at parse.y:12151 #20 0x00005555557580ac in reg_compile (p=0x555555d1f760, str=93825000046904, options=0) at parse.y:12167 ruby#21 0x0000555555746ebb in new_regexp (p=0x555555d1f760, node=0x555555dece68, options=0, loc=0x7fffffff89e8) at parse.y:10072 ruby#22 0x000055555573d1f5 in ruby_yyparse (p=0x555555d1f760) at parse.y:4395 ruby#23 0x000055555574a582 in yycompile0 (arg=93825000404832) at parse.y:5945 ruby#24 0x00005555558c6898 in rb_suppress_tracing (func=0x55555574a470 <yycompile0>, arg=93825000404832) at vm_trace.c:427 ruby#25 0x0000555555748290 in yycompile (vparser=93824999283456, p=0x555555d1f760, fname=93824999283624, line=1) at parse.y:5994 ruby#26 0x00005555557481ae in rb_parser_compile_file_path (vparser=93824999283456, fname=93824999283624, file=93824999283400, start=1) at parse.y:6098 ruby#27 0x00005555557cdd35 in load_file_internal (argp_v=140737488331760) at ruby.c:2023 ruby#28 0x00005555556438c5 in rb_ensure (b_proc=0x5555557cd610 <load_file_internal>, data1=140737488331760, e_proc=0x5555557cddd0 <restore_load_file>, data2=140737488331760) at eval.c:1128 ruby#29 0x00005555557cb68b in load_file (parser=93824999283456, fname=93824999283624, f=93824999283400, script=0, opt=0x7fffffffa468) at ruby.c:2142 ruby#30 0x00005555557cb339 in rb_parser_load_file (parser=93824999283456, fname_v=93824999283624) at ruby.c:2164 ruby#31 0x00005555556ba3e1 in load_iseq_eval (ec=0x555555c0a650, fname=93824999283624) at load.c:579 ruby#32 0x00005555556b857a in require_internal (ec=0x555555c0a650, fname=93824999284352, exception=1) at load.c:1016 ruby#33 0x00005555556b7967 in rb_require_string (fname=93824999284464) at load.c:1105 ruby#34 0x00005555556b7939 in rb_f_require (obj=93824999994824, fname=93824999284464) at load.c:811 ruby#35 0x00005555558b7ae0 in call_cfunc_1 (recv=93824999994824, argc=1, argv=0x7ffff7ecd0a8, func=0x5555556b7920 <rb_f_require>) at vm_insnhelper.c:2348 ruby#36 0x00005555558a8889 in vm_call_cfunc_with_frame (ec=0x555555c0a650, reg_cfp=0x7ffff7fccfa0, calling=0x7fffffffaab0, cd=0x555555d76a10, empty_kw_splat=0) at vm_insnhelper.c:2513 ruby#37 0x000055555589fb5c in vm_call_cfunc (ec=0x555555c0a650, reg_cfp=0x7ffff7fccfa0, calling=0x7fffffffaab0, cd=0x555555d76a10) at vm_insnhelper.c:2538 ruby#38 0x000055555589f22e in vm_call_method_each_type (ec=0x555555c0a650, cfp=0x7ffff7fccfa0, calling=0x7fffffffaab0, cd=0x555555d76a10) at vm_insnhelper.c:2924 ruby#39 0x000055555589ef47 in vm_call_method (ec=0x555555c0a650, cfp=0x7ffff7fccfa0, calling=0x7fffffffaab0, cd=0x555555d76a10) at vm_insnhelper.c:3038 ruby#40 0x0000555555866dbd in vm_call_general (ec=0x555555c0a650, reg_cfp=0x7ffff7fccfa0, calling=0x7fffffffaab0, cd=0x555555d76a10) at vm_insnhelper.c:3075 ruby#41 0x00005555558ae557 in vm_sendish (ec=0x555555c0a650, reg_cfp=0x7ffff7fccfa0, cd=0x555555d76a10, block_handler=0, method_explorer=0x5555558ae5d0 <vm_search_method_wrap>) at vm_insnhelper.c:4021 ruby#42 0x000055555587745b in vm_exec_core (ec=0x555555c0a650, initial=0) at insns.def:801 ruby#43 0x0000555555899b9c in rb_vm_exec (ec=0x555555c0a650, mjit_enable_p=1) at vm.c:1907 ruby#44 0x000055555589aaf0 in rb_iseq_eval_main (iseq=0x555555c1da80) at vm.c:2166 ruby#45 0x0000555555641f0b in rb_ec_exec_node (ec=0x555555c0a650, n=0x555555c1da80) at eval.c:277 ruby#46 0x0000555555641d62 in ruby_run_node (n=0x555555c1da80) at eval.c:335 ruby#47 0x000055555557a188 in main (argc=11, argv=0x7fffffffc848) at main.c:50 (gdb) fr 7 #7 0x0000555555666987 in newobj_init (klass=93824999964192, flags=5, v1=0, v2=0, v3=0, wb_protected=1, objspace=0x555555c0a1c0, obj=93825000456096) at gc.c:2134 2134 if (rgengc_remembered(objspace, (VALUE)obj)) rb_bug("newobj: %s is remembered.", obj_info(obj)); (gdb) p ((struct RVALUE*)obj)->file $1 = 0x65a5992b0fb25ce7 <error: Cannot access memory at address 0x65a5992b0fb25ce7> (gdb) ```

This reverts commit 02b216e. This reverts commit 9b8825b. I found that combining sweep and move is not safe. I don't think that we can do compaction concurrently with _anything_ unless there is a read barrier installed. Here is a simple example. A class object is freed, and during it's free step, it tries to remove itself from its parent's subclass list. However, during the sweep step, the parent class was moved and the "currently being freed" class didn't have references updated yet. So we get a segv like this: ``` (lldb) bt * thread #1, name = 'ruby', stop reason = signal SIGSEGV * frame #0: 0x0000560763e344cb ruby`rb_st_lookup at st.c:320:43 frame #1: 0x0000560763e344cb ruby`rb_st_lookup(tab=0x2f7469672f6e6f72, key=3809, value=0x0000560765bf2270) at st.c:1010 frame #2: 0x0000560763e8f16a ruby`rb_search_class_path at variable.c:99:9 frame #3: 0x0000560763e8f141 ruby`rb_search_class_path at variable.c:145 frame #4: 0x0000560763e8f141 ruby`rb_search_class_path(klass=94589785585880) at variable.c:191 frame #5: 0x0000560763ec744e ruby`rb_vm_bugreport at vm_dump.c:996:17 frame #6: 0x0000560763f5b958 ruby`rb_bug_for_fatal_signal at error.c:675:5 frame #7: 0x0000560763e27dad ruby`sigsegv(sig=<unavailable>, info=<unavailable>, ctx=<unavailable>) at signal.c:955:5 frame #8: 0x00007f8b891d33c0 libpthread.so.0`___lldb_unnamed_symbol1$$libpthread.so.0 + 1 frame #9: 0x0000560763efa8bb ruby`rb_class_remove_from_super_subclasses(klass=94589790314280) at class.c:93:56 frame #10: 0x0000560763d10cb7 ruby`gc_sweep_step at gc.c:2674:2 frame #11: 0x0000560763d1187b ruby`gc_sweep at gc.c:4540:2 frame #12: 0x0000560763d101f0 ruby`gc_start at gc.c:6797:6 frame #13: 0x0000560763d15153 ruby`rb_gc_compact at gc.c:7479:12 frame #14: 0x0000560763eb4eb8 ruby`vm_exec_core at vm_insnhelper.c:5183:13 frame #15: 0x0000560763ea9bae ruby`rb_vm_exec at vm.c:1953:22 frame #16: 0x0000560763eac08d ruby`rb_yield at vm.c:1132:9 frame ruby#17: 0x0000560763edb4f2 ruby`rb_ary_collect at array.c:3186:9 frame ruby#18: 0x0000560763e9ee15 ruby`vm_call_cfunc_with_frame at vm_insnhelper.c:2575:12 frame ruby#19: 0x0000560763eb2e66 ruby`vm_exec_core at vm_insnhelper.c:4177:11 frame #20: 0x0000560763ea9bae ruby`rb_vm_exec at vm.c:1953:22 frame ruby#21: 0x0000560763eac08d ruby`rb_yield at vm.c:1132:9 frame ruby#22: 0x0000560763edb4f2 ruby`rb_ary_collect at array.c:3186:9 frame ruby#23: 0x0000560763e9ee15 ruby`vm_call_cfunc_with_frame at vm_insnhelper.c:2575:12 frame ruby#24: 0x0000560763eb2e66 ruby`vm_exec_core at vm_insnhelper.c:4177:11 frame ruby#25: 0x0000560763ea9bae ruby`rb_vm_exec at vm.c:1953:22 frame ruby#26: 0x0000560763ceee01 ruby`rb_ec_exec_node(ec=0x0000560765afa530, n=0x0000560765b088e0) at eval.c:296:2 frame ruby#27: 0x0000560763cf3b7b ruby`ruby_run_node(n=0x0000560765b088e0) at eval.c:354:12 frame ruby#28: 0x0000560763cee4a3 ruby`main(argc=<unavailable>, argv=<unavailable>) at main.c:50:9 frame ruby#29: 0x00007f8b88e560b3 libc.so.6`__libc_start_main + 243 frame ruby#30: 0x0000560763cee4ee ruby`_start + 46 (lldb) f 9 frame #9: 0x0000560763efa8bb ruby`rb_class_remove_from_super_subclasses(klass=94589790314280) at class.c:93:56 90 91 *RCLASS_EXT(klass)->parent_subclasses = entry->next; 92 if (entry->next) { -> 93 RCLASS_EXT(entry->next->klass)->parent_subclasses = RCLASS_EXT(klass)->parent_subclasses; 94 } 95 xfree(entry); 96 } (lldb) command script import -r misc/lldb_cruby.py lldb scripts for ruby has been installed. (lldb) rp entry->next->klass (struct RMoved) $1 = (flags = 30, destination = 94589792806680, next = 94589784369160) (lldb) ```

This commit adds a check on the ep just like in the mark function. The env can contain null bytes if allocation tracing is enabled. We're seeing errors during autocompaction like this: ``` (lldb) bt 40 * thread #1, name = 'ruby', stop reason = signal SIGABRT frame #0: 0x00007f7d64b6018b libc.so.6`raise + 203 frame #1: 0x00007f7d64b3f859 libc.so.6`abort + 299 frame #2: 0x000055af5f2fefc9 ruby`die at error.c:764:5 frame #3: 0x000055af5f2ff1ac ruby`rb_bug_for_fatal_signal(default_sighandler=0x0000000000000000, sig=11, ctx=0x000055af60bc3340, fmt="") at error.c:804:5 frame #4: 0x000055af5f4bd08f ruby`sigsegv(sig=11, info=0x000055af60bc3470, ctx=0x000055af60bc3340) at signal.c:960:5 frame #5: 0x00007f7d64ebe3c0 libpthread.so.0`__restore_rt frame #6: 0x000055af5f339b0a ruby`gc_ref_update_imemo(objspace=0x000055af60b2b040, obj=0x00007f7d5b513fd0) at gc.c:9046:13 frame #7: 0x000055af5f339172 ruby`gc_update_object_references(objspace=0x000055af60b2b040, obj=0x00007f7d5b513fd0) at gc.c:9307:9 frame #8: 0x000055af5f338e79 ruby`gc_ref_update(vstart=0x00007f7d5b510010, vend=0x00007f7d5b513ff8, stride=40, objspace=0x000055af60b2b040, page=0x000055af62577aa0) at gc.c:9452:21 frame #9: 0x000055af5f337846 ruby`gc_update_references(objspace=0x000055af60b2b040, heap=0x000055af60b2b068) at gc.c:9481:9 frame #10: 0x000055af5f336569 ruby`gc_compact_finish(objspace=0x000055af60b2b040, heap=0x000055af60b2b068) at gc.c:4840:5 frame #11: 0x000055af5f335efb ruby`gc_page_sweep(objspace=0x000055af60b2b040, heap=0x000055af60b2b068, sweep_page=0x000055af63a1eb30) at gc.c:5046:13 frame #12: 0x000055af5f3355c5 ruby`gc_sweep_step(objspace=0x000055af60b2b040, heap=0x000055af60b2b068) at gc.c:5214:19 frame #13: 0x000055af5f33daf6 ruby`gc_sweep_rest(objspace=0x000055af60b2b040) at gc.c:5271:2 frame #14: 0x000055af5f33cacd ruby`gc_sweep(objspace=0x000055af60b2b040) at gc.c:5389:2 frame #15: 0x000055af5f33c21d ruby`gc_marks_rest(objspace=0x000055af60b2b040) at gc.c:7555:5 frame #16: 0x000055af5f324d41 ruby`gc_rest(objspace=0x000055af60b2b040) at gc.c:8457:13 frame ruby#17: 0x000055af5f3297d8 ruby`garbage_collect(objspace=0x000055af60b2b040, reason=45568) at gc.c:8318:9 frame ruby#18: 0x000055af5f344ece ruby`garbage_collect_with_gvl(objspace=0x000055af60b2b040, reason=45568) at gc.c:8632:9 frame ruby#19: 0x000055af5f344e61 ruby`objspace_malloc_gc_stress(objspace=0x000055af60b2b040) at gc.c:10592:9 frame #20: 0x000055af5f32ced1 ruby`objspace_xmalloc0(objspace=0x000055af60b2b040, size=64) at gc.c:10767:5 frame ruby#21: 0x000055af5f32ce11 ruby`ruby_xmalloc0(size=64) at gc.c:10988:12 frame ruby#22: 0x000055af5f32cdac ruby`ruby_xmalloc_body(size=64) at gc.c:10997:12 frame ruby#23: 0x000055af5f329415 ruby`ruby_xmalloc(size=64) at gc.c:12942:12 frame ruby#24: 0x00007f7d611c4fe5 objspace.so`newobj_i(tpval=0x00007f7d5b553770, data=0x000055af639031a0) at object_tracing.c:101:35 frame ruby#25: 0x000055af5f5b283f ruby`tp_call_trace(tpval=0x00007f7d5b553770, trace_arg=0x00007fff1016d398) at vm_trace.c:1115:2 frame ruby#26: 0x000055af5f5b50ec ruby`exec_hooks_body(ec=0x000055af60b2b700, list=0x000055af60b2b920, trace_arg=0x00007fff1016d398) at vm_trace.c:304:3 frame ruby#27: 0x000055af5f5b0f24 ruby`exec_hooks_unprotected(ec=0x000055af60b2b700, list=0x000055af60b2b920, trace_arg=0x00007fff1016d398) at vm_trace.c:333:5 frame ruby#28: 0x000055af5f5b0da8 ruby`rb_exec_event_hooks(trace_arg=0x00007fff1016d398, hooks=0x000055af60b2b920, pop_p=0) at vm_trace.c:378:13 frame ruby#29: 0x000055af5f33f8e2 ruby`rb_exec_event_hook_orig(ec=0x000055af60b2b700, hooks=0x000055af60b2b920, flag=1048576, self=0x00007f7d5b5c08c0, id=0, called_id=0, klass=0x0000000000000000, data=0x00007f7d5b513fd0, pop_p=0) at vm_core.h:1989:5 frame ruby#30: 0x000055af5f334975 ruby`gc_event_hook_body(ec=0x000055af60b2b700, objspace=0x000055af60b2b040, event=1048576, data=0x00007f7d5b513fd0) at gc.c:2083:5 * frame ruby#31: 0x000055af5f3342df ruby`newobj_slowpath_wb_protected [inlined] newobj_slowpath(klass=0x00007f7d5b9d19c8, flags=0x000000000000001a, objspace=0x000055af60b2b040, cr=0x000055af60b2b910, wb_protected=1) at gc.c:2284:9 frame ruby#32: 0x000055af5f33410f ruby`newobj_slowpath_wb_protected(klass=0x00007f7d5b9d19c8, flags=0x000000000000001a, objspace=0x000055af60b2b040, cr=0x000055af60b2b910) at gc.c:2299 frame ruby#33: 0x000055af5f333de9 ruby`newobj_of0(klass=0x00007f7d5b9d19c8, flags=0x000000000000001a, wb_protected=1, cr=0x000055af60b2b910) at gc.c:2338:11 frame ruby#34: 0x000055af5f3227ae ruby`newobj_of(klass=0x00007f7d5b9d19c8, flags=0x000000000000001a, v1=0x000055af657d88a0, v2=0x000055af657d8890, v3=0x0000000000000000, wb_protected=1) at gc.c:2348:17 frame ruby#35: 0x000055af5f322c5b ruby`rb_imemo_new(type=imemo_env, v1=0x000055af657d88a0, v2=0x000055af657d8890, v3=0x0000000000000000, v0=0x00007f7d5b9d19c8) at gc.c:2434:12 frame ruby#36: 0x000055af5f5a3925 ruby`vm_env_new(env_ep=0x000055af657d88a0, env_body=0x000055af657d8890, env_size=4, iseq=0x00007f7d5b9d19c8) at vm_core.h:1363:33 frame ruby#37: 0x000055af5f5a3808 ruby`vm_make_env_each(ec=0x000055af60b2b700, cfp=0x00007f7d6482fc90) at vm.c:801:11 frame ruby#38: 0x000055af5f5a368d ruby`vm_make_env_each(ec=0x000055af60b2b700, cfp=0x00007f7d6482fc20) at vm.c:752:13 frame ruby#39: 0x000055af5f5a368d ruby`vm_make_env_each(ec=0x000055af60b2b700, cfp=0x00007f7d6482fbb0) at vm.c:752:13 (lldb) f 31 frame ruby#31: 0x000055af5f3342df ruby`newobj_slowpath_wb_protected [inlined] newobj_slowpath(klass=0x00007f7d5b9d19c8, flags=0x000000000000001a, objspace=0x000055af60b2b040, cr=0x000055af60b2b910, wb_protected=1) at gc.c:2284:9 2281 } 2282 GC_ASSERT(obj != 0); 2283 newobj_init(klass, flags, wb_protected, objspace, obj); -> 2284 gc_event_hook_prep(objspace, RUBY_INTERNAL_EVENT_NEWOBJ, obj, newobj_fill(obj, 0, 0, 0)); 2285 } 2286 RB_VM_LOCK_LEAVE_CR_LEV(cr, &lev); 2287 (lldb) p obj (VALUE) $3 = 0x00007f7d5b513fd0 (lldb) f 6 frame #6: 0x000055af5f339b0a ruby`gc_ref_update_imemo(objspace=0x000055af60b2b040, obj=0x00007f7d5b513fd0) at gc.c:9046:13 9043 { 9044 rb_env_t *env = (rb_env_t *)obj; 9045 TYPED_UPDATE_IF_MOVED(objspace, rb_iseq_t *, env->iseq); -> 9046 UPDATE_IF_MOVED(objspace, env->ep[VM_ENV_DATA_INDEX_ENV]); 9047 gc_update_values(objspace, (long)env->env_size, (VALUE *)env->env); 9048 } 9049 break; (lldb) p obj (VALUE) $4 = 0x00007f7d5b513fd0 (lldb) ```

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 ruby#17: 0x00000001006412fc miniruby`rb_exec_recursive(func=(miniruby`inspect_ary at array.c:3084), obj=0x000000010d6b4938, arg=0x0000000000000000) at thread.c:5205:12 frame ruby#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 ruby#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 ruby#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 ruby#25: 0x00000001003c440c miniruby`check_funcall_exec(v=6171896792) at vm_eval.c:589:12 frame ruby#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 ruby#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 ruby#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 ruby#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 ruby#30: 0x000000010038fb04 miniruby`rb_check_funcall(recv=4304780496, mid=3233, argc=0, argv=0x0000000000000000) at vm_eval.c:685:12 frame ruby#31: 0x00000001001c469c miniruby`convert_type_with_id(val=4304780496, tname="String", method=3233, raise=0, index=-1) at object.c:3061:15 frame ruby#32: 0x00000001001c4a4c miniruby`rb_check_convert_type_with_id(val=4304780496, type=5, tname="String", method=3233) at object.c:3153:9 frame ruby#33: 0x00000001002d59f8 miniruby`rb_check_string_type(str=4304780496) at string.c:2571:11 frame ruby#34: 0x000000010014b7b0 miniruby`io_encoding_set(fptr=0x0000000100d09ca0, v1=4304780496, v2=4, opt=4) at io.c:11655:19 frame ruby#35: 0x0000000100139a58 miniruby`rb_io_set_encoding(argc=1, argv=0x000000016fdfb450, io=4308334032) at io.c:13497:5 frame ruby#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 ruby#43: 0x0000000100390b08 miniruby`rb_funcall(recv=4308334032, mid=16593, n=1) at vm_eval.c:1137:12 frame ruby#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 3cb23f06f0..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 ruby#17 0x102ad37f0 in rb_gc_impl_start default.c:6816 ruby#18 0x102ad3634 in rb_gc gc.c:3624 ruby#19 0x1031406ec in vm_track_constant_cache vm_insnhelper.c:6342 #20 0x1030b91d8 in vm_ic_track_const_chain vm_insnhelper.c:6356 ruby#21 0x1030b8cf8 in rb_vm_opt_getconstant_path vm_insnhelper.c:6424 ruby#22 0x1030bc1e0 in vm_exec_core insns.def:263 ruby#23 0x1030b55fc in rb_vm_exec vm.c:2585 ruby#24 0x1030fe0ac in rb_iseq_eval_main vm.c:2851 ruby#25 0x102a82588 in rb_ec_exec_node eval.c:281 ruby#26 0x102a81fe0 in ruby_run_node eval.c:319 ruby#27 0x1027f3db4 in rb_main main.c:43 ruby#28 0x1027f3bd4 in main main.c:68 ruby#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

Koichi Sasada and others added 4 commits July 17, 2018 16:21

add transient_heap

f7e4d73

revert merge failure

bfaccaf

add transient_heap.ch

2dff265

introduce LinearTable v2 for small hash

230113d

Signed-off-by: tacinight <[email protected]>

ko1 force-pushed the transient_heap branch from 2dff265 to 71d2c42 Compare October 30, 2018 06:38

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introduce LinearTable v2 for small hash #5

introduce LinearTable v2 for small hash #5

yimin-zhao commented Jul 29, 2018

introduce LinearTable v2 for small hash #5

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introduce LinearTable v2 for small hash #5

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yimin-zhao commented Jul 29, 2018