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ReDoS: stop spuriously matching everything when encountering an unsupported charclass #13468

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ReDoS: stop spuriously matching everything when encountering an unsupported charclass #13468

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a38f024
stop spuriously matching everything when encountering an unsupported …
erik-krogh Jun 15, 2023
1aff977
fix QL-for-QL warning
erik-krogh Jun 15, 2023
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14 changes: 12 additions & 2 deletions shared/regex/codeql/regex/nfa/NfaUtils.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -451,7 +451,15 @@ module Make<RegexTreeViewSig TreeImpl> {
}

bindingset[char]
override predicate matches(string char) { not hasChildThatMatches(cc, char) }
override predicate matches(string char) {
not hasChildThatMatches(cc, char) and
(
// detect unsupported char classes that doesn't match anything (e.g. `\p{L}` in ruby), and don't report any matches
hasChildThatMatches(cc, _)
or
not exists(cc.getAChild()) // [^] still matches everything
)
}
}

/**
Expand Down Expand Up @@ -536,7 +544,9 @@ module Make<RegexTreeViewSig TreeImpl> {

bindingset[char]
override predicate matches(string char) {
not classEscapeMatches(charClass.toLowerCase(), char)
not classEscapeMatches(charClass.toLowerCase(), char) and
// detect unsupported char classes (e.g. `\p{L}` in ruby), and don't report any matches
classEscapeMatches(charClass.toLowerCase(), _)
}
}

Expand Down