From d292a9b98ce03c76dbe13138d20b9fbf613cc02d Mon Sep 17 00:00:00 2001 From: Daniel Colson Date: Wed, 24 Apr 2024 22:20:48 -0400 Subject: [Bug #20453] segfault in Regexp timeout https://bugs.ruby-lang.org/issues/20228 started freeing `stk_base` to avoid a memory leak. But `stk_base` is sometimes stack allocated (using `xalloca`), so the free only works if the regex stack has grown enough to hit `stack_double` (which uses `xmalloc` and `xrealloc`). To reproduce the problem on master and 3.3.1: ```ruby Regexp.timeout = 0.001 /^(a*)x$/ =~ "a" * 1000000 + "x"' ``` Some details about this potential fix: `stk_base == stk_alloc` on [init](https://github.com/ruby/ruby/blob/dde99215f2bc60c22a00fc941ff7f714f011e920/regexec.c#L1153), so if `stk_base != stk_alloc` we can be sure we called [`stack_double`](https://github.com/ruby/ruby/blob/dde99215f2bc60c22a00fc941ff7f714f011e920/regexec.c#L1210) and it's safe to free. It's also safe to free if we've [saved](https://github.com/ruby/ruby/blob/dde99215f2bc60c22a00fc941ff7f714f011e920/regexec.c#L1187-L1189) the stack to `msa->stack_p`, since we do the `stk_base != stk_alloc` check before saving. This matches the check we do inside [`stack_double`](https://github.com/ruby/ruby/blob/dde99215f2bc60c22a00fc941ff7f714f011e920/regexec.c#L1221) --- test/ruby/test_regexp.rb | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'test/ruby') diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb index c996b1785a..03d96954b4 100644 --- a/test/ruby/test_regexp.rb +++ b/test/ruby/test_regexp.rb @@ -1827,6 +1827,17 @@ class TestRegexp < Test::Unit::TestCase end; end + def test_bug_20453 + assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}") + begin; + Regexp.timeout = 0.001 + + assert_raise(Regexp::TimeoutError) do + /^(a*)x$/ =~ "a" * 1000000 + "x" + end + end; + end + def per_instance_redos_test(global_timeout, per_instance_timeout, expected_timeout) assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}") global_timeout = #{ EnvUtil.apply_timeout_scale(global_timeout).inspect } -- cgit v1.2.3