From 0ade5611df9f981005eed32b369d1e699e520221 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADt=20Ondruch?= <vondruch@redhat.com>
Date: Thu, 10 Feb 2022 13:26:44 +0100
Subject: [PATCH] Don't query `RubyVM::FrozenCore` for class path.
The `RubyVM::FrozenCore` class path is corrupted during GC cycle and
returns random garbage, which might result in segfault.
But since it is easy to detect the `RubyVM::FrozenCore`, just provide
the class path explicitly as a workaround.
Other possibility would be to ignore `RubyVM::FrozenCore` simlarly as
TracePoint API does:
https://github.com/ruby/ruby/blob/46f6575157d4c2f6bbd5693896e26a65037e5552/vm_trace.c#L411
---
vm.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/vm.c b/vm.c
index 8ce8b279d4..3d189fa63a 100644
--- a/vm.c
+++ b/vm.c
@@ -446,7 +446,15 @@ rb_dtrace_setup(rb_execution_context_t *ec, VALUE klass, ID id,
}
type = BUILTIN_TYPE(klass);
if (type == T_CLASS || type == T_ICLASS || type == T_MODULE) {
- VALUE name = rb_class_path(klass);
+ VALUE name = Qnil;
+ /*
+ * Special treatment for rb_mRubyVMFrozenCore wchi is broken by GC.
+ * https://bugs.ruby-lang.org/issues/18257
+ */
+ if (klass == rb_mRubyVMFrozenCore)
+ name = rb_str_new_cstr("RubyVM::FrozenCore");
+ else
+ name = rb_class_path(klass);
const char *classname, *filename;
const char *methodname = rb_id2name(id);
if (methodname && (filename = rb_source_location_cstr(&args->line_no)) != 0) {
--
2.34.1