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Fix overflow parsing large float exponents #20

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Merged
tjol merged 1 commit into from
Mar 6, 2026
Merged

Fix overflow parsing large float exponents #20

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5 changes: 4 additions & 1 deletion src/parser.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1048,7 +1048,10 @@ static bool _parse_decimal_float(kdl_str number, kdl_value* val, kdl_owned_strin
int digit = c - '0';
if (state == exponent || state == exponent_nodigit) {
state = exponent;
explicit_exponent = explicit_exponent * 10 + digit;
// stop parsing beyond rough heuristic, avoids overflow
if (explicit_exponent < 285) {
explicit_exponent = explicit_exponent * 10 + digit;
}
} else {
decimal_mantissa = decimal_mantissa * 10 + digit;
if (state == before_decimal) {
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28 changes: 28 additions & 0 deletions tests/parser_test.c
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Expand Up @@ -388,6 +388,33 @@ static void test_parser_detects_version(void)
kdl_destroy_parser(parser_v2);
}

static void test_extreme_float(void)
{
char const* const kdl_text = "node1 1e4294967296";

kdl_str doc = kdl_str_from_cstr(kdl_text);
kdl_parser* parser = kdl_create_string_parser(doc, 0);

// test all events
kdl_event_data* ev;

ev = kdl_parser_next_event(parser);
ASSERT(ev->event == KDL_EVENT_START_NODE);

ev = kdl_parser_next_event(parser);
ASSERT(ev->event == KDL_EVENT_ARGUMENT);
ASSERT(ev->value.type == KDL_TYPE_NUMBER);
ASSERT(ev->value.number.type == KDL_NUMBER_TYPE_STRING_ENCODED);

ev = kdl_parser_next_event(parser);
ASSERT(ev->event == KDL_EVENT_END_NODE);

ev = kdl_parser_next_event(parser);
ASSERT(ev->event == KDL_EVENT_EOF);

kdl_destroy_parser(parser);
}

void TEST_MAIN(void)
{
run_test("Parser: basics", &test_basics);
Expand All @@ -399,4 +426,5 @@ void TEST_MAIN(void)
run_test("Parser: type can't be number", &test_number_type);
run_test("Parser: BOM treated as whitespace", &test_bom);
run_test("Parser: KDLv1 and KDLv2 both supported", &test_parser_detects_version);
run_test("Parser: parse extreme floating point", &test_extreme_float);
}