diff options
| author | Peter Zhu <[email protected]> | 2023-11-20 14:55:50 -0500 |
|---|---|---|
| committer | Peter Zhu <[email protected]> | 2023-11-20 16:57:24 -0500 |
| commit | f376163194686079452ddfd0af61ab505172c07c () | |
| tree | 3f7629e0e4678aaedebfdfbe54f4abc2e33b957b | |
| parent | 103bbd21f884c279fc8368dac5cc4f62d68231af (diff) | |
Fix crash when evacuating generic ivar
When transitioning generic instance variable objects to too complex, we set the shape first before performing inserting the new gen_ivtbl. The st_insert for the new gen_ivtbl could allocate and cause a GC. If that happens, then it will crash because the object will have a too complex shape but not yet be backed by a st_table. This commit changes the order so that the insert happens first before the new shape is set. The following script reproduces the issue: ``` o = [] o.instance_variable_set(:@a, 1) i = 0 o = Object.new while RubyVM::Shape.shapes_available > 0 o.instance_variable_set(:"@i#{i}", 1) i += 1 end ary = 1_000.times.map { [] } GC.stress = true ary.each do |o| o.instance_variable_set(:@a, 1) o.instance_variable_set(:@b, 1) end ```
| -rw-r--r-- | test/ruby/test_shapes.rb | 22 | ||||
| -rw-r--r-- | variable.c | 2 |
2 files changed, 23 insertions, 1 deletions
@@ -277,6 +277,28 @@ class TestShapes < Test::Unit::TestCase end; end def test_run_out_of_shape_for_module_ivar assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}") begin; @@ -1399,12 +1399,12 @@ rb_obj_convert_to_too_complex(VALUE obj, st_table *table) struct gen_ivtbl *ivtbl = xmalloc(sizeof(struct gen_ivtbl)); ivtbl->as.complex.table = table; #if SHAPE_IN_BASIC_FLAGS rb_shape_set_shape_id(obj, OBJ_TOO_COMPLEX_SHAPE_ID); #else ivtbl->shape_id = OBJ_TOO_COMPLEX_SHAPE_ID; #endif - st_insert(gen_ivs, (st_data_t)obj, (st_data_t)ivtbl); } RB_VM_LOCK_LEAVE(); } |