From: "rosenfeld (Rodrigo Rosenfeld Rosas)" <rr.rosas@...>
Date: 2013-02-07T00:01:27+09:00
Subject: [ruby-core:51923] [ruby-trunk - Feature #7791] Let symbols be garbage collected


Issue #7791 has been updated by rosenfeld (Rodrigo Rosenfeld Rosas).


It depends. If the process eats up all system memory it will eventually crash and release all memory used by the Ruby process, right? This doesn't seem like a really big problem once the limit is reached and the application crashed.

But anyway, I believe that DoS attacks are usually targeted at applications. If you make your application always crash for some actions, then I'd say your DoS attack is successful.
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Feature #7791: Let symbols be garbage collected
https://bugs.ruby-lang.org/issues/7791#change-35922

Author: rosenfeld (Rodrigo Rosenfeld Rosas)
Status: Feedback
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: next minor


Lots of Denial-of-Service security vulnerabilities exploited in Ruby programs rely on symbols not being collected by garbage collector.

Ideally I'd prefer symbols and strings to behave exactly the same being just alternate ways of writing strings but I'll let this to another ticket.

This one simply asks for symbols to be allowed to be garbage collected when low on memory. Maybe one could set up some up-limit memory constraints dedicated to storing symbols. That way, the most accessed symbols would remain in that memory region and the least used ones would be reclaimed when the memory for symbols is over and a new symbol is created.

Or you could just allow symbols to be garbage collected any time. Any reasons why this would be a bad idea? Any performance benchmark demonstrating how using symbols instead of strings would make a real-world software perform much better?

Currently I only see symbols slowing down processing because people don't want to worry about it and will often use something like ActiveSupport Hash#with_indifferent_access or some other method to convert a string to symbol or vice versa...


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