[Bug]: Overly permissive regular expression range

Issue は tests/integration/stackscripts/test_stackscripts.py の 95 行目を指している。そこにある正規表現と既存のカバレッジを調べる。文字範囲が意図した文字だけを受け付けることを確認し、該当するテストまたは式を更新して、関連する統合テストを実行する。

CLI Version

v5.56.2

Command

https://github.com/linode/linode-cli/blob/fafe73e1f48a48ab9cbdf9b01f679e041f6bf3fa/tests/integration/stackscripts/test_stackscripts.py#L95-L95

It's easy to write a regular expression range that matches a wider range of characters than you intended. /[a-zA-z]/ matches all lowercase and all uppercase letters, as you would expect, but it also matches the characters: `[ \ ] ^ _ ``.

Another common problem is failing to escape the dash character in a regular expression. An unescaped dash is interpreted as part of a range. For example, in the character class [a-zA-Z0-9%=.,-_] the last character range matches the 55 characters between , and _ (both included), which overlaps with the range [0-9] and is clearly not intended by the writer.

Output

No response

Expected Behavior

[CWE-20

Actual Behavior

Improper Neutralization of Special Elements used in a Command in Shell-quote
Exploiting CVE-2021-42740
no-obscure-range
The regex [,-.]
CWE-20.

Steps to Reproduce

POC

The following code is intended to check whether a string is a valid 6 digit hex color.

import re
def is_valid_hex_color(color):
    return re.match(r'^#[0-9a-fA-f]{6}$', color) is not None

However, the A-f range is overly large and matches every uppercase character. It would parse a "color" like #XXYYZZ as valid.

The fix is to use an uppercase A-F range instead.

import re
def is_valid_hex_color(color):
    return re.match(r'^#[0-9a-fA-F]{6}$', color) is not None

Recommendation

Avoid any confusion about which characters are included in the range by writing unambiguous regular expressions. Always check that character ranges match only the expected characters.