Issue #21441 has been updated by luke-gru (Luke Gruber). I opened a PR [here](https://github.com/ruby/ruby/pull/13643). This may need to be backported. ---------------------------------------- Bug #21441: SEGV during thread cleanup if profiler calls thread_profiles_frames at wrong time https://bugs.ruby-lang.org/issues/21441#change-113779 * Author: luke-gru (Luke Gruber) * Status: Open * ruby -v: 3.5.0 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- During thread cleanup, if a ruby sampling profiler calls `thread_profile_frames` at just the wrong time, the ec's stack is cleared but the CFP still exists on the EC, so `thread_profile_frames` assumes it can walk the stack and crashes. In `rb_ec_clear_vm_stack`, it should set `cfp` to `NULL` before clearing the stack. If during `rc_ec_clear_vm_stack` the process gets a signal and this thread handles it and calls `thread_profile_frames`, the early return check of `if (!cfp)` fails, it continues and crashes in this function. -- https://bugs.ruby-lang.org/