[ruby-core:103134] [Ruby master Bug#17765] Segmentation fault when calling String#gsub

[jean.boussier@gmail.com]

Issue #17765 has been updated by byroot (Jean Boussier).


> But without success so far.

I wouldn't be surprised if the bug wasn't in `gsub` itself, but in some C extension that would generate a faulty string on which `gsub` would trip. I see you have `thrift` loaded for instance. IIRC that's a binary format parser like protobuf etc, it might be creating strings improperly.

This could prove very hard to track. 

----------------------------------------
Bug #17765: Segmentation fault when calling String#gsub
https://bugs.ruby-lang.org/issues/17765#change-91207

* Author: lenwood (Paul Martensen)
* Status: Open
* Priority: Normal
* ruby -v: ruby 2.7.2p137 (2020-10-01 revision 5445e04352) [x86_64-linux-musl]
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
We recently had a ruby segfault occuring while invoking `String#gsub`. 

The line in the code looks like this:

``` ruby
def sanitize_for_prometheus(string_or_symbol)
  reg = /[^a-zA-Z_0-9]/
  string_or_symbol.to_s.downcase.gsub(reg, '_')
end
```

And we've tried to replicate the segfault (on a different machine) with this script:

```rb
def sanitize_for_prometheus(string_or_symbol)
  reg = /[^a-zA-Z_0-9]/
  string_or_symbol.to_s.downcase.gsub(reg, '_')
end

def rand_string_or_symbol
  @o ||= [('a'..'z').to_a, ('A'..'Z').to_a, (0..9).to_a, '-', '.'].flatten
  str = @o.sample(50).join
  rand > 0.5 ? str.to_sym : str
end

loop { sanitize_for_prometheus rand_string_or_symbol }
```

But without success so far. I have attached a shortened version of the log file for reference.

 


---Files--------------------------------
segfault.log (60.8 KB)
segfault_gsub.rb (343 Bytes)


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