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Fix CVE-2025-67125: prevent signed counter overflow in LeafPattern::match #168

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Fix CVE-2025-67125: prevent signed counter overflow in LeafPattern::match #168

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20 changes: 16 additions & 4 deletions docopt_private.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
#define docopt_docopt_private_h

#include <vector>
#include <limits>
#include <memory>
#include <unordered_set>
#include <assert.h>
Expand All @@ -34,6 +35,16 @@ namespace std {

namespace docopt {


static inline long safe_add_long(long a, long b) {
const long LMAX = std::numeric_limits<long>::max();
const long LMIN = std::numeric_limits<long>::min();
if (b > 0 && a > LMAX - b) return LMAX;
if (b < 0 && a < LMIN - b) return LMIN;
return a + b;
}


class Pattern;
class LeafPattern;

Expand Down Expand Up @@ -450,11 +461,12 @@ namespace docopt {
if (getValue().isLong()) {
long val = 1;
if (same_name == collected.end()) {
collected.push_back(match.second);
match.second->setValue(value{val});
collected.push_back(match.second);
match.second->setValue(value{val});
} else if ((**same_name).getValue().isLong()) {
val += (**same_name).getValue().asLong();
(**same_name).setValue(value{val});
val = safe_add_long((**same_name).getValue().asLong(), val);
if (val < 0) { val = std::numeric_limits<long>::max(); }
(**same_name).setValue(value{val});
} else {
(**same_name).setValue(value{val});
}
Expand Down