From: duerst@...
Date: 2017-03-22T10:55:17+00:00
Subject: [ruby-dev:50031] [Ruby trunk Bug#13352] RegExp infinite looping

Issue #13352 has been updated by duerst (Martin Dürst).


I haven't yet had time to analyze the regular expression in detail. Are you sure this is really an infinite loop, and not just a case of exponentially slow processing (e.g. similar to stackoverflow.com/questions/16580665/node-js-regex-engine-fails-on-large-input)?

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Bug #13352: RegExp infinite looping
https://bugs.ruby-lang.org/issues/13352#change-63729

* Author: jumnichi_kose (小瀬 淳一)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 2.3.3p222 (2016-11-21 revision 56859) [x64-mingw32],  ruby 2.2.4p230 (2015-12-16 revision 53155) [i386-mingw32]
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
----------------------------------------
ruby entered an infinite loop with the following three steps.

~~~ ruby
r = /(?=\W)\W?(?:(?:(?:\/\*<)?[\'\"]?([\w_\$]+)[\'\"]?(?:>\*\/\s+this)?|(this))\.(\$scope|json)|([\'\"](?:\$scope|json)[\'\"]))((\.)(inputObjects)|(\.)(spreadSheets)(?:\.[\'\"]?([^\.\'\"\|\s,]+)[\'\"]?|\[[\'\"]?((?:[^\'\"\]\[]*|\[[^\]]*\])*)[\'\"]?\])(\.)(model))\s*(?:\.[\'\"]?([^\.\'\"\|\s,]+)[\'\"]?|\[[\'\"]?((?:[^\'\"\]\[]*|\[[^\]]*\])*)[\'\"]?\])/
txt = ".model |,| 'anController'.$scope.inputObjects['fieldName .../* !! comment ...*/"
txt.scan r
~~~

Node.js also falls into an infinite loop.
~~~ javascript
var r = /(?=\W)\W?(?:(?:(?:\/\*<)?[\'\"]?([\w_\$]+)[\'\"]?(?:>\*\/\s+this)?|(this))\.(\$scope|json)|([\'\"](?:\$scope|json)[\'\"]))((\.)(inputObjects)|(\.)(spreadSheets)(?:\.[\'\"]?([^\.\'\"\|\s,]+)[\'\"]?|\[[\'\"]?((?:[^\'\"\]\[]*|\[[^\]]*\])*)[\'\"]?\])(\.)(model))\s*(?:\.[\'\"]?([^\.\'\"\|\s,]+)[\'\"]?|\[[\'\"]?((?:[^\'\"\]\[]*|\[[^\]]*\])*)[\'\"]?\])/
var txt = ".model |,| 'anController'.$scope.inputObjects['fieldName .../* !! comment ...*/"

var s =r.exec (txt)

console.log(s)


~~~





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