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Change stack depth limit to 256 #1657

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Change stack depth limit to 256 #1657

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74f362f
Change stack depth limit to 256
baylesj Mar 15, 2026
37dc755
run clang format
baylesj Mar 15, 2026
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8 changes: 4 additions & 4 deletions src/lib_json/json_reader.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,7 @@
// Define JSONCPP_DEPRECATED_STACK_LIMIT as an appropriate integer at compile
// time to change the stack limit
#if !defined(JSONCPP_DEPRECATED_STACK_LIMIT)
#define JSONCPP_DEPRECATED_STACK_LIMIT 1000
#define JSONCPP_DEPRECATED_STACK_LIMIT 256
#endif

static size_t const stackLimit_g =
Expand Down Expand Up @@ -1932,7 +1932,7 @@ void CharReaderBuilder::strictMode(Json::Value* settings) {
(*settings)["allowDroppedNullPlaceholders"] = false;
(*settings)["allowNumericKeys"] = false;
(*settings)["allowSingleQuotes"] = false;
(*settings)["stackLimit"] = 1000;
(*settings)["stackLimit"] = 256;
(*settings)["failIfExtra"] = true;
(*settings)["rejectDupKeys"] = true;
(*settings)["allowSpecialFloats"] = false;
Expand All @@ -1949,7 +1949,7 @@ void CharReaderBuilder::setDefaults(Json::Value* settings) {
(*settings)["allowDroppedNullPlaceholders"] = false;
(*settings)["allowNumericKeys"] = false;
(*settings)["allowSingleQuotes"] = false;
(*settings)["stackLimit"] = 1000;
(*settings)["stackLimit"] = 256;
(*settings)["failIfExtra"] = false;
(*settings)["rejectDupKeys"] = false;
(*settings)["allowSpecialFloats"] = false;
Expand All @@ -1965,7 +1965,7 @@ void CharReaderBuilder::ecma404Mode(Json::Value* settings) {
(*settings)["allowDroppedNullPlaceholders"] = false;
(*settings)["allowNumericKeys"] = false;
(*settings)["allowSingleQuotes"] = false;
(*settings)["stackLimit"] = 1000;
(*settings)["stackLimit"] = 256;
(*settings)["failIfExtra"] = true;
(*settings)["rejectDupKeys"] = false;
(*settings)["allowSpecialFloats"] = false;
Expand Down
10 changes: 10 additions & 0 deletions src/test_lib_json/main.cpp
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Expand Up @@ -3355,6 +3355,16 @@ JSONTEST_FIXTURE_LOCAL(CharReaderTest, parseWithStackLimit) {
JSONTEST_ASSERT_THROWS(
reader->parse(doc, doc + std::strlen(doc), &root, &errs));
}
// Default stack limit should reject deeply nested input (regression test for
// stack exhaustion from fuzz input like [[[[...]]]])
{
Json::CharReaderBuilder defaultBuilder;
Json::String nested(300, '[');
CharReaderPtr reader(defaultBuilder.newCharReader());
Json::String errs;
JSONTEST_ASSERT_THROWS(reader->parse(
nested.data(), nested.data() + nested.size(), &root, &errs));
}

#endif // JSON_USE_EXCEPTION
}
Expand Down
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