Issue #21865 has been updated by jeremyevans0 (Jeremy Evans). Eregon (Benoit Daloze) wrote in #note-4:
Interestingly enough I noticed I believe the same (or very similar) segfault yesterday when [trying to test the behavior](https://github.com/truffleruby/truffleruby/pull/4151#discussion_r2771020336) of `rb_scan_args_kw()` with [RB_SCAN_ARGS_KEYWORDS](https://github.com/ruby/ruby/blob/86dba8cfaeabb3b86df921da24b3243b9ce4ab2a/i...) but not passing a Hash as last argument. Given that the documentation states:
The final argument should be a hash treated as keywords.
"should" seems like it should not segfault if the should doesn't hold.
I wrote the `rb_scan_args_kw` support, the `should` here should be `must`. If you want behavior where the last argument may not be a hash, you should use `RB_SCAN_ARGS_LAST_HASH_KEYWORDS`, not `RB_SCAN_ARGS_KEYWORDS`. However, I don't think that's the issue here. My understanding of this issue is the cfunc is operating on an unexpected VM stack frame, which seems to be a more serious problem. We need to ensure the cfunc is operating on the VM stack frame it expects to be operating on, and not on a stack frame related to a signal. ---------------------------------------- Bug #21865: Crash on signal raise https://bugs.ruby-lang.org/issues/21865#change-116293 * Author: dodecadaniel (Daniel Colson) * Status: Open * ruby -v: 4.0.1 * Backport: 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONTNEED, 4.0: REQUIRED ---------------------------------------- This crashes on Ruby 4.0 ``` sh $ ruby -e 'loop { File.open("./test.rb", kwarg: true) {} }'& [1] 93542 $ kill -TERM 93542 [BUG] Segmentation fault at 0x000000000000001f ``` Note the `0x1f` (i.e. 15, which is `Signal.list["TERM"]`). While preparing the exception we pass argc=2, with argv containing the signal class and the fixnum for the TERM. https://github.com/ruby/ruby/blob/86dba8cfaeabb3b86df921da24b3243b9ce4ab2a/t... That eventually gets passed through to https://github.com/ruby/ruby/blob/86dba8cfaeabb3b86df921da24b3243b9ce4ab2a/c..., where we set the signal fixnum as `last` and treat it like a hash. But 0x1f is a fixnum, not a hash, so that crashes. `rb_scan_args_keyword_p` returns true in this case even though `last` is not a hash because kw_flag is `RB_SCAN_ARGS_PASS_CALLED_KEYWORDS` (which I think causes it to look at the last frame to see if keywords were passed, rather than checking whether `last` is a hash. I don't think we push any frames in this case, so it's looking at whatever the last frame before the signal happened to be). Should we still check that it's a hash regardless? I believe the bug was introduced in https://github.com/ruby/ruby/commit/64f508ade8c8535b7d3ecdd217886aa52fddd43c. -- https://bugs.ruby-lang.org/