Issue #19554 has been updated by peterzhu2118 (Peter Zhu). Thanks for the reply @ioquatix! I haven't looked too much into ASAN, I'll look into it further. My main concern with ASAN is the need for Ruby to be compiled with it turned on and that additional code may need to be added into native extensions to support it. Both of these are barriers to entry compared to Valgrind. In the [Valgrind manual](https://valgrind.org/docs/manual/mc-manual.html#mc-manual.clientreqs), it looks like there's a `VALGRIND_MAKE_MEM_DEFINED` function. Maybe that can be used to mark the regions as valid. ---------------------------------------- Bug #19554: Invalid memory access detected by Valgrind when using Fibers https://bugs.ruby-lang.org/issues/19554#change-102582 * Author: peterzhu2118 (Peter Zhu) * Status: Open * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- This issue was originally reported here: https://github.com/Shopify/ruby_memcheck/issues/14 Running the script shown below using `valgrind --trace-children=yes --num-callers=500 ruby test.rb` outputs a lot of invalid memory access errors. I've shown a few sample errors below. I am able to reproduce this issue on the master branch (commit [1e9a218ade](https://github.com/ruby/ruby/commit/1e9a218ade3af90c18f42e3fea08e2fcea81222a)), 3.2, 3.1, 3.0. ```ruby require "bundler/inline" gemfile do source "https://rubygems.org" gem "graphql" end module Example class FooType < GraphQL::Schema::Object field :id, ID, null: false end class FooSource < GraphQL::Dataloader::Source def fetch(ids) ids end end class QueryType < GraphQL::Schema::Object field :foo, Example::FooType do argument :foo_id, GraphQL::Types::ID, required: false, loads: Example::FooType end def foo(foo: nil); end end class Schema < GraphQL::Schema query Example::QueryType use GraphQL::Dataloader def self.object_from_id(id, ctx) ctx.dataloader.with(Example::FooSource).request(id) end end end Example::Schema.execute(<<-GRAPHQL) { foo(fooId: "Other") { id } } GRAPHQL ``` ``` ==203957== Use of uninitialised value of size 8 ==203957== at 0x3453FD: vm_exec_core (vm.inc:4411) ==203957== by 0x357EFB: rb_vm_exec (vm.c:2366) ==203957== by 0x354E44: invoke_block (vm.c:1384) ==203957== by 0x355759: invoke_iseq_block_from_c (vm.c:1440) ==203957== by 0x355759: invoke_block_from_c_proc (vm.c:1538) ==203957== by 0x355759: vm_invoke_proc (vm.c:1568) ==203957== by 0x355DF4: rb_vm_invoke_proc (vm.c:1589) ==203957== by 0x48F695: rb_fiber_start (cont.c:2513) ==203957== by 0x48CCF8: fiber_entry (cont.c:831) ==203957== ==203957== Invalid write of size 8 ==203957== at 0x48C407: fiber_pool_stack_reset (cont.c:325) ==203957== by 0x48C4E9: fiber_pool_vacancy_reset (cont.c:364) ==203957== by 0x48CBB0: fiber_pool_stack_release (cont.c:752) ==203957== by 0x48CECF: fiber_stack_release (cont.c:874) ==203957== by 0x48FC9F: fiber_switch (cont.c:2726) ==203957== by 0x4901F9: fiber_resume_kw (cont.c:2906) ==203957== by 0x490235: rb_fiber_resume_kw (cont.c:2912) ==203957== by 0x4903B7: rb_fiber_m_resume (cont.c:2973) ==203957== by 0x3337D6: ractor_safe_call_cfunc_m1 (vm_insnhelper.c:3166) ==203957== by 0x33440A: vm_call_cfunc_with_frame_ (vm_insnhelper.c:3357) ==203957== by 0x3345E1: vm_call_cfunc_with_frame (vm_insnhelper.c:3385) ==203957== by 0x3398E5: vm_sendish (vm_insnhelper.c:5225) ==203957== by 0x341203: vm_exec_core (insns.def:835) ==203957== by 0x357EFB: rb_vm_exec (vm.c:2366) ==203957== by 0x354E44: invoke_block (vm.c:1384) ==203957== by 0x355759: invoke_iseq_block_from_c (vm.c:1440) ==203957== by 0x355759: invoke_block_from_c_proc (vm.c:1538) ==203957== by 0x355759: vm_invoke_proc (vm.c:1568) ==203957== by 0x355DF4: rb_vm_invoke_proc (vm.c:1589) ==203957== by 0x48F695: rb_fiber_start (cont.c:2513) ==203957== by 0x48CCF8: fiber_entry (cont.c:831) ==203957== Address 0x9bad008 is in a rw- anonymous segment ``` -- https://bugs.ruby-lang.org/