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authorStan Lo <stan.lo@shopify.com>2023-01-16 20:42:51 +0000
committerPeter Zhu <peter@peterzhu.ca>2023-01-17 08:01:19 -0500
commitdf6b72b8ff7af16a56fa48f3b4abb1d8850f4d1c (patch)
tree67fd7da4f7a26e5e1af3153eba8581c5dc49c400 /vm_insnhelper.c
parent9399352a43253e2905d76d21774fb0301069197b (diff)
downloadruby-df6b72b8ff7af16a56fa48f3b4abb1d8850f4d1c.tar.gz
Avoid checking interrupt when loading iseq
The interrupt check will unintentionally release the VM lock when loading an iseq. And this will cause issues with the `debug` gem's [`ObjectSpace.each_iseq` method](https://github.com/ruby/debug/blob/0fcfc28acae33ec1c08068fb7c33703cfa681fa7/ext/debug/iseq_collector.c#L61-L67), which wraps iseqs with a wrapper and exposes their internal states when they're actually not ready to be used. And when that happens, errors like this would occur and kill the `debug` gem's thread: ``` DEBUGGER: ReaderThreadError: uninitialized InstructionSequence ┃ DEBUGGER: Disconnected. ┃ ["/opt/rubies/ruby-3.2.0/lib/ruby/gems/3.2.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:247:in `absolute_path'", ┃ "/opt/rubies/ruby-3.2.0/lib/ruby/gems/3.2.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:247:in `block in iterate_iseq'", ┃ "/opt/rubies/ruby-3.2.0/lib/ruby/gems/3.2.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:246:in `each_iseq'", ... ``` A way to reproduce the issue is to satisfy these conditions at the same time: 1. `debug` gem calling `ObjectSpace.each_iseq` (e.g. [activating a `LineBreakpoint`](https://github.com/ruby/debug/blob/0fcfc28acae33ec1c08068fb7c33703cfa681fa7/lib/debug/breakpoint.rb#L246)). 2. A large amount of iseq being loaded from another thread (possibly through the `bootsnap` gem). 3. 1 and 2 iterating through the same iseq(s) at the same time. Because this issue requires external dependencies and a rather complicated timing setup to reproduce, I wasn't able to write a test case for it. But here's some pseudo code to help reproduce it: ```rb require "debug/session" Thread.new do 100.times do ObjectSpace.each_iseq do |iseq| iseq.absolute_path end end end sleep 0.1 load_a_bunch_of_iseq possibly_through_bootsnap ``` [Bug #19348] Co-authored-by: Peter Zhu <peter@peterzhu.ca>
Diffstat (limited to 'vm_insnhelper.c')
-rw-r--r--vm_insnhelper.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 29753f1800..0ce7fb6cc7 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -405,6 +405,17 @@ vm_push_frame(rb_execution_context_t *ec,
vm_push_frame_debug_counter_inc(ec, cfp, type);
}
+void
+rb_vm_pop_frame_no_int(rb_execution_context_t *ec)
+{
+ rb_control_frame_t *cfp = ec->cfp;
+
+ if (VM_CHECK_MODE >= 4) rb_gc_verify_internal_consistency();
+ if (VMDEBUG == 2) SDR();
+
+ ec->cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
+}
+
/* return TRUE if the frame is finished */
static inline int
vm_pop_frame(rb_execution_context_t *ec, rb_control_frame_t *cfp, const VALUE *ep)