Bug #20937
Updated by akiellor (Andrew Kiellor) 13 days ago
We've observed a recurring "can't set length of shared string" error in production emerging from the `aws-sdk-s3` library when using it's client encryption features. The sdk in this mode uses OpenSSL::Cipher in decrypt mode with a String buffer. It appears that under some circumstances the buffer becomes a "shared string" and is no longer compatible with the requirements of OpenSSL::Cipher#update.
I've attached a reproduction scenario using only the ruby standard library.
``` shell
$ ruby -v
ruby 3.3.6 (2024-11-05 revision 75015d4c1f) +YJIT [arm64-darwin23]
$ ruby scripty.rb
scripty.rb:32:in `update': can't set length of shared string (RuntimeError)
from scripty.rb:32:in `block (2 levels) in <main>'
from scripty.rb:31:in `each'
from scripty.rb:31:in `block in <main>'
from /nix/store/fhmbmmzr4h5yax66nl2x44rrdf039b3s-ruby-3.3.6/lib/ruby/3.3.0/tempfile.rb:447:in `create'
from scripty.rb:26:in `<main>'
```
The attached script has a few different read patterns, some fail and some do not.
Credit for isolating this issue goes to [@simoleone](https://bugs.ruby-lang.org/users/55425).