From 2cee81ae6b3ed2ee783f62b82362c7c57e11fa0c Mon Sep 17 00:00:00 2001 From: Niels Lohmann Date: Sat, 5 Sep 2026 16:43:48 +0200 Subject: [PATCH] Honor allow_exceptions=false for excessive array/object size (out_of_range.408) The SAX DOM parsers' start_object()/start_array() threw out_of_range.408 directly via JSON_THROW when a binary format (CBOR/UBJSON/BJData) declared a container size exceeding max_size(), bypassing the allow_exceptions flag that every other malformed-input error path in these classes honors via parse_error(). This meant that json::from_cbor(data, true, false) etc. could still throw (or abort under JSON_NOEXCEPTION) instead of returning a discarded value, contrary to the allow_exceptions=false contract. Route all four call sites (two in json_sax_dom_parser, two in json_sax_dom_callback_parser) through parse_error() instead, matching the existing error-handling pattern used elsewhere in this file. Behavior is unchanged when allow_exceptions is true (the default); the exception message and type are identical. Signed-off-by: Niels Lohmann --- include/nlohmann/detail/input/json_sax.hpp | 8 +++---- single_include/nlohmann/json.hpp | 8 +++---- tests/src/unit-regression2.cpp | 26 ++++++++++++++++++++++ 3 files changed, 34 insertions(+), 8 deletions(-) diff --git a/include/nlohmann/detail/input/json_sax.hpp b/include/nlohmann/detail/input/json_sax.hpp index aa10275d3..d1da99bb4 100644 --- a/include/nlohmann/detail/input/json_sax.hpp +++ b/include/nlohmann/detail/input/json_sax.hpp @@ -250,7 +250,7 @@ class json_sax_dom_parser if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size())) { - JSON_THROW(out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back())); + return parse_error(0, "", out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back())); } return true; @@ -299,7 +299,7 @@ class json_sax_dom_parser if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size())) { - JSON_THROW(out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back())); + return parse_error(0, "", out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back())); } return true; @@ -569,7 +569,7 @@ class json_sax_dom_callback_parser // check object limit if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size())) { - JSON_THROW(out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back())); + return parse_error(0, "", out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back())); } } return true; @@ -679,7 +679,7 @@ class json_sax_dom_callback_parser // check array limit if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size())) { - JSON_THROW(out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back())); + return parse_error(0, "", out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back())); } } diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp index 616e6ef69..817da77d4 100644 --- a/single_include/nlohmann/json.hpp +++ b/single_include/nlohmann/json.hpp @@ -9778,7 +9778,7 @@ class json_sax_dom_parser if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size())) { - JSON_THROW(out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back())); + return parse_error(0, "", out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back())); } return true; @@ -9827,7 +9827,7 @@ class json_sax_dom_parser if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size())) { - JSON_THROW(out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back())); + return parse_error(0, "", out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back())); } return true; @@ -10097,7 +10097,7 @@ class json_sax_dom_callback_parser // check object limit if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size())) { - JSON_THROW(out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back())); + return parse_error(0, "", out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back())); } } return true; @@ -10207,7 +10207,7 @@ class json_sax_dom_callback_parser // check array limit if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size())) { - JSON_THROW(out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back())); + return parse_error(0, "", out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back())); } } diff --git a/tests/src/unit-regression2.cpp b/tests/src/unit-regression2.cpp index a607d2878..736957cd2 100644 --- a/tests/src/unit-regression2.cpp +++ b/tests/src/unit-regression2.cpp @@ -1637,4 +1637,30 @@ TEST_CASE("regression test - parser callback must not lose a duplicate key's pri } } +TEST_CASE("regression test - excessive binary container size honors allow_exceptions=false") +{ + // CBOR array with declared length 2^63 + const std::vector cbor = {0x9b, 0x80, 0, 0, 0, 0, 0, 0, 0}; + // CBOR map with declared length 2^63 + const std::vector cbor_m = {0xbb, 0x80, 0, 0, 0, 0, 0, 0, 0}; + // UBJSON array with declared length 2^63-1 + const std::vector ubj = {'[', '#', 'L', 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; + // BJData array with declared length 2^63-1 (little endian) + const std::vector bjd = {'[', '#', 'L', 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f}; + + // allow_exceptions=false must report failure instead of throwing/aborting + CHECK(json::from_cbor(cbor, true, false).is_discarded()); + CHECK(json::from_cbor(cbor_m, true, false).is_discarded()); + CHECK(json::from_ubjson(ubj, true, false).is_discarded()); + CHECK(json::from_bjdata(bjd, true, false).is_discarded()); + + // allow_exceptions=true (the default) must still throw exactly as before + CHECK_THROWS_AS(json::from_cbor(cbor), json::out_of_range); + CHECK_THROWS_WITH(json::from_cbor(cbor), + "[json.exception.out_of_range.408] excessive array size: 9223372036854775808"); + + // regression guard: a genuinely truncated CBOR input must remain discarded + CHECK(json::from_cbor(std::vector {0x9b, 0, 0, 0, 0, 0, 0, 0, 0x02}, true, false).is_discarded()); +} + DOCTEST_CLANG_SUPPRESS_WARNING_POP