From 389b9471c819f974b821e4a1399cf20aa0628658 Mon Sep 17 00:00:00 2001 From: KJ Tsanaktsidis Date: Sat, 8 Jan 2022 15:21:46 +1100 Subject: [PATCH] Fix interpreter crash caused by RUBY_INTERNAL_EVENT_NEWOBJ + Ractors When a Ractor is created whilst a tracepoint for RUBY_INTERNAL_EVENT_NEWOBJ is active, the interpreter crashes. This is because during the early setup of the Ractor, the stdio objects are created, which allocates Ruby objects, which fires the tracepoint. However, the tracepoint machinery tries to dereference the control frame (ec->cfp->pc), which isn't set up yet and so crashes with a null pointer dereference. Fix this by not firing GC tracepoints if cfp isn't yet set up. --- gc.c | 1 + test/objspace/test_ractor.rb | 16 ++++++++++++++++ 2 files changed, 17 insertions(+) create mode 100644 test/objspace/test_ractor.rb diff --git a/gc.c b/gc.c index d77dc2cda4..044775739b 100644 --- a/gc.c +++ b/gc.c @@ -2210,6 +2210,7 @@ rb_objspace_set_event_hook(const rb_event_flag_t event) static void gc_event_hook_body(rb_execution_context_t *ec, rb_objspace_t *objspace, const rb_event_flag_t event, VALUE data) { + // if (UNLIKELY(!ec->cfp)) return; const VALUE *pc = ec->cfp->pc; if (pc && VM_FRAME_RUBYFRAME_P(ec->cfp)) { /* increment PC because source line is calculated with PC-1 */ diff --git a/test/objspace/test_ractor.rb b/test/objspace/test_ractor.rb new file mode 100644 index 0000000000..d1b703b58e --- /dev/null +++ b/test/objspace/test_ractor.rb @@ -0,0 +1,16 @@ +require "test/unit" +require "objspace" + +class TestObjSpaceRactor < Test::Unit::TestCase + def test_tracing_does_not_crash + ObjectSpace.trace_object_allocations do + r = Ractor.new do + obj = 'a' * 1024 + Ractor.yield obj + end + + r.take + r.take + end + end +end -- 2.33.1