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Merge pull request github#13164 from erik-krogh/polyQhelp
ReDoS: add another example to the qhelp in poly-redos, showing how to just limit the length of the input
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‎java/ql/src/Security/CWE/CWE-730/PolynomialReDoS.qhelp

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@@ -15,8 +15,7 @@
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</p>
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<sample language="java">
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Pattern.compile("^\\s+|\\s+$").matcher(text).replaceAll("") // BAD
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</sample>
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Pattern.compile("^\\s+|\\s+$").matcher(text).replaceAll("") // BAD</sample>
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<p>
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</p>
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<sample language="java">
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"^0\\.\\d+E?\\d+$""
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</sample>
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"^0\\.\\d+E?\\d+$"" </sample>
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<p>
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</example>
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<example>
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<p>
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Sometimes it is unclear how a regular expression can be rewritten to
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avoid the problem. In such cases, it often suffices to limit the
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length of the input string. For instance, the following
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regular expression is used to match numbers, and on some non-number
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inputs it can have quadratic time complexity:
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</p>
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<sample language="java">
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Pattern.matches("^(\\+|-)?(\\d+|(\\d*\\.\\d*))?(E|e)?([-+])?(\\d+)?$", str); </sample>
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<p>
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It is not immediately obvious how to rewrite this regular expression
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to avoid the problem. However, you can mitigate performance issues by limiting the length
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to 1000 characters, which will always finish in a reasonable amount
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of time.
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</p>
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<sample language="java">
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if (str.length() &gt; 1000) {
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throw new IllegalArgumentException("Input too long");
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}
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Pattern.matches("^(\\+|-)?(\\d+|(\\d*\\.\\d*))?(E|e)?([-+])?(\\d+)?$", str); </sample>
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</example>
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<include src="ReDoSReferences.inc.qhelp"/>
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</qhelp>

‎javascript/ql/src/Performance/PolynomialReDoS.qhelp

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@@ -15,8 +15,7 @@
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</p>
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<sample language="javascript">
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text.replace(/^\s+|\s+$/g, ''); // BAD
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</sample>
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text.replace(/^\s+|\s+$/g, ''); // BAD</sample>
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<p>
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</p>
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<sample language="javascript">
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/^0\.\d+E?\d+$/.test(str) // BAD
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</sample>
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/^0\.\d+E?\d+$/.test(str) // BAD</sample>
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<p>
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</example>
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<example>
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<p>
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Sometimes it is unclear how a regular expression can be rewritten to
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avoid the problem. In such cases, it often suffices to limit the
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length of the input string. For instance, the following
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regular expression is used to match numbers, and on some non-number
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inputs it can have quadratic time complexity:
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</p>
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<sample language="javascript">
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/^(\+|-)?(\d+|(\d*\.\d*))?(E|e)?([-+])?(\d+)?$/.test(str) // BAD</sample>
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<p>
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It is not immediately obvious how to rewrite this regular expression
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to avoid the problem. However, you can mitigate performance issues by limiting the length
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to 1000 characters, which will always finish in a reasonable amount
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of time.
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</p>
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<sample language="javascript">
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if (str.length &gt; 1000) {
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throw new Error("Input too long");
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}
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/^(\+|-)?(\d+|(\d*\.\d*))?(E|e)?([-+])?(\d+)?$/.test(str)</sample>
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</example>
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<include src="ReDoSReferences.inc.qhelp"/>
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</qhelp>

‎python/ql/src/Security/CWE-730/PolynomialReDoS.qhelp

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Original file line numberDiff line numberDiff line change
@@ -15,8 +15,7 @@
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</p>
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<sample language="python">
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re.sub(r"^\s+|\s+$", "", text) # BAD
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</sample>
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re.sub(r"^\s+|\s+$", "", text) # BAD</sample>
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<p>
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</p>
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<sample language="python">
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^0\.\d+E?\d+$ # BAD
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</sample>
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^0\.\d+E?\d+$ # BAD</sample>
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<p>
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</example>
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<example>
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<p>
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Sometimes it is unclear how a regular expression can be rewritten to
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avoid the problem. In such cases, it often suffices to limit the
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length of the input string. For instance, the following
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regular expression is used to match numbers, and on some non-number
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inputs it can have quadratic time complexity:
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</p>
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<sample language="python">
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match = re.search(r'^(\+|-)?(\d+|(\d*\.\d*))?(E|e)?([-+])?(\d+)?$', str) </sample>
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<p>
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It is not immediately obvious how to rewrite this regular expression
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to avoid the problem. However, you can mitigate performance issues by limiting the length
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to 1000 characters, which will always finish in a reasonable amount
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of time.
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</p>
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<sample language="python">
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if len(str) &gt; 1000:
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raise ValueError("Input too long")
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match = re.search(r'^(\+|-)?(\d+|(\d*\.\d*))?(E|e)?([-+])?(\d+)?$', str) </sample>
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</example>
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<include src="ReDoSReferences.inc.qhelp"/>
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</qhelp>

‎ruby/ql/src/queries/security/cwe-1333/PolynomialReDoS.qhelp

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Original file line numberDiff line numberDiff line change
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</p>
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<sample language="ruby">
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text.gsub!(/^\s+|\s+$/, '') # BAD
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</sample>
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text.gsub!(/^\s+|\s+$/, '') # BAD</sample>
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<p>
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</p>
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<sample language="ruby">
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/^0\.\d+E?\d+$/ # BAD
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</sample>
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/^0\.\d+E?\d+$/ # BAD</sample>
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<p>
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</example>
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<example>
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<p>
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Sometimes it is unclear how a regular expression can be rewritten to
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avoid the problem. In such cases, it often suffices to limit the
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length of the input string. For instance, the following
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regular expression is used to match numbers, and on some non-number
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inputs it can have quadratic time complexity:
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</p>
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<sample language="ruby">
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is_matching = /^(\+|-)?(\d+|(\d*\.\d*))?(E|e)?([-+])?(\d+)?$/.match?(str)</sample>
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<p>
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It is not immediately obvious how to rewrite this regular expression
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to avoid the problem. However, you can mitigate performance issues by limiting the length
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to 1000 characters, which will always finish in a reasonable amount
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of time.
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</p>
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<sample language="ruby">
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if str.length &gt; 1000
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raise ArgumentError, "Input too long"
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end
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is_matching = /^(\+|-)?(\d+|(\d*\.\d*))?(E|e)?([-+])?(\d+)?$/.match?(str)</sample>
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</example>
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<include src="ReDoSReferences.inc.qhelp"/>
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</qhelp>

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