Issue #22412 has been updated by peterzhu2118 (Peter Zhu). Backport changed from 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN to 3.3: DONTNEED, 3.4: DONTNEED, 4.0: DONTNEED Thank you for the bug report. I have a fix here: https://github.com/ruby/ruby/pull/19251 ---------------------------------------- Bug #22412: Assertion Failed: vm_ep_in_heap_p_:env->ep == ep https://bugs.ruby-lang.org/issues/22412#change-119376 * Author: 0599jiangyc@gmail.com (Yuancheng Jiang) * Status: Open * Backport: 3.3: DONTNEED, 3.4: DONTNEED, 4.0: DONTNEED ---------------------------------------- The following code: ```ruby pr = proc {|a, b| }.curry.dup pr.call(1) ``` (also `lambda {|a, b| }.curry.clone[1]`, or `define_method(:m, &proc {|a, b| }.curry); m(1)` which dups the proc internally) Resulted in this output (RUBY_DEBUG build): ``` ../vm.c:281: Assertion Failed: vm_ep_in_heap_p_:env->ep == ep ruby 4.1.0dev (2026-10-07) +PRISM [x86_64-linux] -- Ruby level backtrace information ---------------------------------------- min.rb:2:in '<main>' min.rb:2:in 'proc' -- C level backtrace information ------------------------------------------- (vm_ep_in_heap_p_+0x1a2) vm.c:281 (VM_ENV_ESCAPED_P+0xae) vm.c:295 (vm_make_env_each+0x133) vm.c:1120 (vm_make_env_object+0x8) vm.c:1217 (rb_vm_make_proc_lambda) vm.c:1720 (vm_call0_body+0x100a) ../vm_eval.c:164 (rb_call0+0x4c5) ../vm_eval.c:101 (iterate_method+0x144) ../vm_eval.c:896 (rb_iterate0+0x298) ../vm_eval.c:1506 (rb_block_call_kw+0x42) ../vm_eval.c:1580 (make_curry_proc) proc.c:4525 (curry+0x118) proc.c:4545 (vm_yield_with_cfunc+0x172) ../vm_insnhelper.c:5275 ``` `rb_func_proc_dup` (proc.c) gives the copy its own ep inside the new `cfunc_proc_t`, but copies `ep[VM_ENV_DATA_INDEX_ENV]` from the source. For a curried proc that slot already holds an env object (created when `curry` called `Kernel#proc`/`lambda` on the ifunc block), whose `env->ep` points into the *source* proc's storage. The duplicate's ep and its env therefore disagree. Only the debug assertion fires in our testing; we did not observe a crash or ASan report on a non-debug build, even after dropping the source proc and running `GC.start`/`GC.compact`. (Related area: Bug #20950, whose backport note mentions a `vm_ep_in_heap_p_` VM_ASSERT failure; possibly also related to Bug #22113.) To reproduce: ``` ruby ./min.rb ``` Commit: ``` 3296d5c99ce005e4698fb27a405e01d766ad2647 (2026-09-15); also reproduced on master 9ce0df671980d669cbab8afc48124c7453897533 (2026-10-07) ``` Build configuration: ``` ../configure --disable-install-doc CC=clang-18 cflags="-fsanitize=address -fno-omit-frame-pointer -DUSE_MN_THREADS=0" cppflags="-DRUBY_DEBUG=1" optflags="-O1" debugflags="-g" ``` Operating System: ``` Ubuntu 24.04.4 LTS (x86_64), clang 18.1.3 ``` *This bug was found by [fusion-fuzz](https://github.com/fusion-fuzz/fusion-fuzz)* -- https://bugs.ruby-lang.org/