[ruby-core:113150] [Ruby master Bug#19529] [BUG] ObjectSpace::WeakMap can segfault after compaction
From:
"jprokop (Jarek Prokop) via ruby-core" <ruby-core@...>
Date:
2023-04-06 10:18:06 UTC
List:
ruby-core #113150
Issue #19529 has been updated by jprokop (Jarek Prokop).
Please consider adding a guard to the test that comes with https://github.com/ruby/ruby/commit/3dc8cde70078ccb38f5f4b0818ad5eecded01bd5 .
There can be a case of not compiling with compaction, which we do with Ruby 3.1 on Fedora for ppc64le due to another bug.
In the case of unsupported compaction, the test failure looks like so:
```
1) Error:
TestWeakMap#test_compaction_bug_19529:
NotImplementedError: compact() function is unimplemented on this machine
```
Since we patch [0] Ruby to not implement the methods unless a compilation-time flag is defined, we see NotImplementedError and therefore can do a simple
```
def test_compaction_bug_19529
skip('Compaction not supported') unless GC.respond_to?(:compact)
```
in the offending test.
But maybe something similar to the `CompactionSupportInspector` in `test/ruby/test_gc_compact.rb` is better for the overall consistency in tests: https://github.com/ruby/ruby/blob/f269fae07e68117cd4ab42d889136ea37e6d3913/test/ruby/test_gc_compact.rb#L12
[0] https://src.fedoraproject.org/rpms/ruby/blob/86c35ad5cfca4e73134e6438295c68beeb1ef2cf/f/ruby-3.2.0-define-unsupported-gc-compaction-methods-as-rb_f_notimplement.patch
----------------------------------------
Bug #19529: [BUG] ObjectSpace::WeakMap can segfault after compaction
https://bugs.ruby-lang.org/issues/19529#change-102686
* Author: byroot (Jean Boussier)
* Status: Closed
* Priority: Normal
* ruby -v: 3.2.1, 2.7.5p203
* Backport: 2.7: WONTFIX, 3.0: REQUIRED, 3.1: DONE, 3.2: REQUIRED
----------------------------------------
Reproduction script:
```ruby
wm = ObjectSpace::WeakMap.new
obj = Object.new
100.times do |i|
GC.compact
wm[i] = obj # [BUG] Segmentation fault at 0x0000000000000001
end
```
Crash report:
```
/tmp/weakmap.rb:5: [BUG] Segmentation fault at 0x0000000000000003
ruby 3.2.1 (2023-02-08 revision 31819e82c8) [arm64-darwin22]
-- Crash Report log information --------------------------------------------
See Crash Report log file in one of the following locations:
* ~/Library/Logs/DiagnosticReports
* /Library/Logs/DiagnosticReports
for more details.
Don't forget to include the above Crash Report log file in bug reports.
-- Control frame information -----------------------------------------------
c:0005 p:---- s:0023 e:000022 CFUNC :[]=
c:0004 p:0016 s:0017 e:000015 BLOCK /tmp/weakmap.rb:5 [FINISH]
c:0003 p:---- s:0012 e:000011 CFUNC :times
c:0002 p:0017 s:0008 E:0025b0 EVAL /tmp/weakmap.rb:3 [FINISH]
c:0001 p:0000 s:0003 E:0010b0 DUMMY [FINISH]
-- Ruby level backtrace information ----------------------------------------
/tmp/weakmap.rb:3:in `<main>'
/tmp/weakmap.rb:3:in `times'
/tmp/weakmap.rb:5:in `block in <main>'
/tmp/weakmap.rb:5:in `[]='
-- Machine register context ------------------------------------------------
x0: 0x000000016da8a6b0 x1: 0x000000016da8a6a8 x2: 0x000000000000003d
x3: 0x0000000000000001 x4: 0x0000000000000000 x5: 0x0000000000000b00
x6: 0x0000600002db4b00 x7: 0x0000000000000000 x18: 0x0000000000000000
x19: 0x000000016da8a6a8 x20: 0x000000000000003d x21: 0x0000000000000003
x22: 0x0000000000000001 x23: 0x00000001023df7b8 x24: 0x0000000000000001
x25: 0x0000000000000000 x26: 0x00006000027bdf80 x27: 0xffffffffffffffff
x28: 0xffffffffffffffff lr: 0x0000000102ca28f0 fp: 0x000000016da8a680
sp: 0x000000016da8a640
-- C level backtrace information -------------------------------------------
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_vm_bugreport+0x9a0) [0x102d3ba98]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_bug_for_fatal_signal+0x160) [0x102b5fe14]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(sig_do_nothing+0x0) [0x102c9a354]
/usr/lib/system/libsystem_platform.dylib(_sigtramp+0x38) [0x19b63c2a4]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_st_update+0x328) [0x102ca28f0]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_st_update+0x328) [0x102ca28f0]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(wmap_aset+0x90) [0x102b88e9c]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_call_cfunc_with_frame+0xe8) [0x102d2fc7c]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_sendish+0x4cc) [0x102d31fdc]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_exec_core+0x239c) [0x102d136c8]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_vm_exec+0xad4) [0x102d26bf0]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(invoke_block_from_c_bh+0x398) [0x102d36438]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_yield_1+0x7c) [0x102d1f208]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(int_dotimes+0x148) [0x102bff3ec]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_call_cfunc_with_frame+0xe8) [0x102d2fc7c]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_sendish+0x4cc) [0x102d31fdc]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_exec_core+0x2350) [0x102d1367c]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_vm_exec+0xad4) [0x102d26bf0]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_ec_exec_node+0x12c) [0x102b6b4ac]
/opt/rubies/3.2.1/lib/libruby.3.2.dylib(ruby_run_node+0x60) [0x102b6b318]
/opt/rubies/3.2.1/bin/ruby(main+0x68) [0x102377f34]
```
Seems to happens since 2.7.
--
https://bugs.ruby-lang.org/
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