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require exact element count in as<std::array<T, N>> #1203

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Merged
redboltz merged 1 commit into from
Nov 4, 2026
Merged

require exact element count in as<std::array<T, N>> #1203

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2 changes: 1 addition & 1 deletion include/msgpack/v1/adaptor/cpp11/array.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,7 @@ template <typename T, std::size_t N>
struct as<std::array<T, N>, typename std::enable_if<msgpack::has_as<T>::value>::type> {
std::array<T, N> operator()(msgpack::object const& o) const {
if(o.type != msgpack::type::ARRAY) { throw msgpack::type_error(); }
if(o.via.array.size > N) { throw msgpack::type_error(); }
if(o.via.array.size != N) { throw msgpack::type_error(); }
return detail::array::as_impl<T, N>::as(o);
}
};
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13 changes: 13 additions & 0 deletions test/security_fixes_cpp11.cpp
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Expand Up @@ -65,6 +65,19 @@ BOOST_AUTO_TEST_CASE(array_char_str_no_overread)
BOOST_CHECK_EQUAL(a[2], 'Z'); // untouched
}

// A5: as<std::array<T, N>> reads exactly N elements through as_impl, so a wire
// array shorter than N (or empty) must throw instead of reading past the end.
BOOST_AUTO_TEST_CASE(array_as_short_array_throws)
{
using tp = std::chrono::system_clock::time_point;
msgpack::object_handle oh0 = msgpack::unpack("\x90", 1); // [] -> would deref null
BOOST_CHECK_THROW((oh0.get().as<std::array<tp, 2> >()), msgpack::type_error);

const char b1[] = "\x91\xd6\xff\x00\x00\x00\x00"; // [ts32] -> would read ptr[1..2]
msgpack::object_handle oh1 = msgpack::unpack(b1, sizeof(b1) - 1);
BOOST_CHECK_THROW((oh1.get().as<std::array<tp, 3> >()), msgpack::type_error);
}

// B1: moving a (v2) unpacker must not leave the parser referencing the
// moved-from object's buffer hook.
BOOST_AUTO_TEST_CASE(unpacker_move_buffer_hook)
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