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Avoid double-free on duplicate enum names during BFBS deserialization #9012

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Avoid double-free on duplicate enum names during BFBS deserialization #9012

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29f6b07
Avoid double-free on duplicate enum names during BFBS deserialization
steadytao Apr 3, 2026
767128b
Free duplicate enums rejected during parsing
steadytao Apr 3, 2026
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2 changes: 1 addition & 1 deletion include/flatbuffers/idl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -245,9 +245,9 @@ class SymbolTable {
}

bool Add(const std::string& name, T* e) {
vec.emplace_back(e);
auto it = dict.find(name);
if (it != dict.end()) return true;
vec.emplace_back(e);
dict[name] = e;
return false;
}
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4 changes: 3 additions & 1 deletion src/idl_parser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3126,8 +3126,10 @@ CheckedError Parser::StartEnum(const std::string& name, bool is_union,
enum_def.is_union = is_union;
enum_def.defined_namespace = current_namespace_;
const auto qualified_name = current_namespace_->GetFullyQualifiedName(name);
if (enums_.Add(qualified_name, &enum_def))
if (enums_.Add(qualified_name, &enum_def)) {
delete &enum_def;
return Error("enum already exists: " + qualified_name);
}
enum_def.underlying_type.base_type =
is_union ? BASE_TYPE_UTYPE : BASE_TYPE_INT;
enum_def.underlying_type.enum_def = &enum_def;
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29 changes: 29 additions & 0 deletions tests/test.cpp
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Expand Up @@ -1203,6 +1203,34 @@ void EmbeddedSchemaAccess() {
EmbeddedSchemaAccessByType<StatT>();
}

void DuplicateEnumNameBinarySchemaTest() {
static const uint8_t duplicate_enum_name_schema[] = {
0x10, 0x00, 0x00, 0x00, 0x42, 0x46, 0x42, 0x53, 0x08, 0x00, 0x0c, 0x00,
0x04, 0x00, 0x08, 0x00, 0x08, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00,
0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00,
0x30, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x10, 0x00,
0x04, 0x00, 0x08, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x0c, 0x00, 0x00, 0x00,
0x4c, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x28, 0x00, 0x00, 0x00,
0x0c, 0x00, 0x12, 0x00, 0x04, 0x00, 0x08, 0x00, 0x00, 0x00, 0x0c, 0x00,
0x0c, 0x00, 0x00, 0x00, 0x44, 0x00, 0x00, 0x00, 0x28, 0x00, 0x00, 0x00,
0x18, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00, 0x06, 0x00, 0x05, 0x00,
0x06, 0x00, 0x00, 0x00, 0x00, 0x03, 0x06, 0x00, 0x08, 0x00, 0x07, 0x00,
0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x0d, 0x00, 0x00, 0x00, 0x44, 0x75, 0x70, 0x6c,
0x69, 0x63, 0x61, 0x74, 0x65, 0x45, 0x6e, 0x75, 0x6d, 0x00, 0x00, 0x00,
0x0d, 0x00, 0x00, 0x00, 0x44, 0x75, 0x70, 0x6c, 0x69, 0x63, 0x61, 0x74,
0x65, 0x45, 0x6e, 0x75, 0x6d, 0x00, 0x00, 0x00};

flatbuffers::Verifier verifier(duplicate_enum_name_schema,
sizeof(duplicate_enum_name_schema));
TEST_EQ(reflection::VerifySchemaBuffer(verifier), true);

flatbuffers::Parser parser;
TEST_EQ(parser.Deserialize(duplicate_enum_name_schema,
sizeof(duplicate_enum_name_schema)),
false);
}

void NestedVerifierTest() {
// Create a nested monster.
flatbuffers::FlatBufferBuilder nested_builder;
Expand Down Expand Up @@ -1848,6 +1876,7 @@ int FlatBufferTests(const std::string& tests_data_path) {
FlexBuffersFloatingPointTest();
FlatbuffersIteratorsTest();
WarningsAsErrorsTest();
DuplicateEnumNameBinarySchemaTest();
NestedVerifierTest();
SizeVerifierTest();
PrivateAnnotationsLeaks();
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