8000 Fix memory leak in Prism's RubyVM::InstructionSequence.new · ruby/ruby@34b407a · GitHub
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Fix memory leak in Prism's RubyVM::InstructionSequence.new
[Bug #21394] There are two ways to make RubyVM::InstructionSequence.new raise which would cause the options->scopes to leak memory: 1. Passing in any (non T_FILE) object where the to_str raises. 2. Passing in a T_FILE object where String#initialize_dup raises. This is because rb_io_path dups the string. Example 1: 10.times do 100_000.times do RubyVM::InstructionSequence.new(nil) rescue TypeError end puts `ps -o rss= -p #{$$}` end Before: 13392 17104 20256 23920 27264 30432 33584 36752 40032 43232 After: 9392 11072 11648 11648 11648 11712 11712 11712 11744 11744 Example 2: require "tempfile" MyError = Class.new(StandardError) String.prepend(Module.new do def initialize_dup(_) if $raise_on_dup raise MyError else super end end end) Tempfile.create do |f| 10.times do 100_000.times do $raise_on_dup = true RubyVM::InstructionSequence.new(f) rescue MyError else raise "MyError was not raised during RubyVM::InstructionSequence.new" end puts `ps -o rss= -p #{$$}` ensure $raise_on_dup = false end end Before: 14080 18512 22000 25184 28320 31600 34736 37904 41088 44256 After: 12016 12464 12880 12880 12880 12912 12912 12912 12912 12912
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‎iseq.c

Lines changed: 13 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1327,6 +1327,15 @@ pm_iseq_compile_with_option(VALUE src, VALUE file, VALUE realpath, VALUE line, V
13271327
ln = NUM2INT(line);
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StringValueCStr(file);
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1330+
bool parse_file = false;
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if (RB_TYPE_P(src, T_FILE)) {
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parse_file = true;
1333+
src = rb_io_path(src);
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}
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else {
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src = StringValue(src);
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}
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pm_parse_result_t result = { 0 };
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pm_options_line_set(&result.options, NUM2INT(line));
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pm_options_scopes_init(&result.options, 1);
@@ -1349,16 +1358,15 @@ pm_iseq_compile_with_option(VALUE src, VALUE file, VALUE realpath, VALUE line, V
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VALUE script_lines;
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VALUE error;
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1352-
if (RB_TYPE_P(src, T_FILE)) {
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VALUE filepath = rb_io_path(src);
1354-
error = pm_load_parse_file(&result, filepath, ruby_vm_keep_script_lines ? &script_lines : NULL);
1355-
RB_GC_GUARD(filepath);
1361+
if (parse_file) {
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error = pm_load_parse_file(&result, src, ruby_vm_keep_script_lines ? &script_lines : NULL);
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}
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else {
1358-
src = StringValue(src);
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error = pm_parse_string(&result, src, file, ruby_vm_keep_script_lines ? &script_lines : NULL);
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}
13611367

1368+
RB_GC_GUARD(src);
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if (error == Qnil) {
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int error_state;
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iseq = pm_iseq_new_with_opt(&result.node, name, file, realpath, ln, NULL, 0, ISEQ_TYPE_TOP, &option, &error_state);

‎test/ruby/test_iseq.rb

Lines changed: 50 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -297,6 +297,56 @@ def test_invalid_source
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assert_raise(TypeError, bug11159) {compile(1)}
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end
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def test_invalid_source_no_memory_leak
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# [Bug #21394]
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assert_no_memory_leak(["-rtempfile"], "#{<<-"begin;"}", "#{<<-'end;'}", rss: true)
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code = proc do |t|
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RubyVM::InstructionSequence.new(nil)
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rescue TypeError
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else
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raise "TypeError was not raised during RubyVM::InstructionSequence.new"
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end
309+
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10.times(&code)
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begin;
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1_000_000.times(&code)
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end;
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# [Bug #21394]
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# RubyVM::InstructionSequence.new calls rb_io_path, which dups the string
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# and can leak memory if the dup raises
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assert_no_memory_leak(["-rtempfile"], "#{<<-"begin;"}", "#{<<-'end;'}", rss: true)
319+
MyError = Class.new(StandardError)
320+
String.prepend(Module.new do
321+
def initialize_dup(_)
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if $raise_on_dup
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raise MyError
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else
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super
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end
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end
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end)
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code = proc do |t|
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Tempfile.create do |f|
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$raise_on_dup = true
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t.times do
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RubyVM::InstructionSequence.new(f)
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rescue MyError
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else
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raise "MyError was not raised during RubyVM::InstructionSequence.new"
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end
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ensure
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$raise_on_dup = false
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end
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end
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code.call(100)
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begin;
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code.call(1_000_000)
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end;
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end
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300350
def test_frozen_string_literal_compile_option
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$f = 'f'
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line = __LINE__ + 2

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