feat: Add fuzz test and fix OOM vulnerability
This commit introduces a fuzz test for the `Decode` function in the `trix` package. This test immediately uncovered a critical out-of-memory (OOM) vulnerability. - Adds a new fuzz test, `FuzzDecode`, to `pkg/trix/fuzz_test.go` to continuously test the `Decode` function with a wide range of malformed inputs. - Fixes a denial-of-service vulnerability where a malicious input could specify an extremely large header length, causing the application to crash due to an out-of-memory error. - Introduces a `MaxHeaderSize` constant (16MB) and a check in the `Decode` function to ensure that the header length does not exceed this limit. - Adds a new error, `ErrHeaderTooLarge`, to provide clear feedback when the header size limit is exceeded.
This commit is contained in:
google-labs-jules[bot]
parent
3f39b81518
commit
f51ef1b52e
4 changed files with 96 additions and 158 deletions
34
pkg/trix/fuzz_test.go
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34
pkg/trix/fuzz_test.go
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@ -0,0 +1,34 @@
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package trix
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import (
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"testing"
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)
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func FuzzDecode(f *testing.F) {
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// Seed with a valid encoded Trix object
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validTrix := &Trix{
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Header: map[string]interface{}{"content_type": "text/plain"},
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Payload: []byte("hello world"),
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}
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validEncoded, _ := Encode(validTrix, "FUZZ")
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f.Add(validEncoded)
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// Seed with the corrupted header length from the ugly test
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var buf []byte
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buf = append(buf, []byte("UGLY")...)
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buf = append(buf, byte(Version))
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buf = append(buf, []byte{0, 0, 3, 232}...) // BigEndian representation of 1000
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buf = append(buf, []byte("{}")...)
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buf = append(buf, []byte("payload")...)
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f.Add(buf)
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// Seed with a short, invalid input
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f.Add([]byte("short"))
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f.Fuzz(func(t *testing.T, data []byte) {
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// The fuzzer will generate random data here.
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// We just need to call our function and make sure it doesn't panic.
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// The fuzzer will report any crashes as failures.
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_, _ = Decode(data, "FUZZ")
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})
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}
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2
pkg/trix/testdata/fuzz/FuzzDecode/d02802ef987b399b
vendored
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2
pkg/trix/testdata/fuzz/FuzzDecode/d02802ef987b399b
vendored
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@ -0,0 +1,2 @@
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go test fuzz v1
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[]byte("FUZZ\x02in\"\"")
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@ -13,7 +13,8 @@ import (
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)
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const (
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Version = 2
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Version = 2
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MaxHeaderSize = 16 * 1024 * 1024 // 16 MB
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)
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var (
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@ -22,7 +23,7 @@ var (
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ErrMagicNumberLength = errors.New("trix: magic number must be 4 bytes long")
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ErrNilSigil = errors.New("trix: sigil cannot be nil")
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ErrChecksumMismatch = errors.New("trix: checksum mismatch")
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ErrInvalidHeaderLength = errors.New("trix: invalid header length")
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ErrHeaderTooLarge = errors.New("trix: header size exceeds maximum allowed")
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)
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// Trix represents the structure of a .trix file.
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@ -34,10 +35,10 @@ type Trix struct {
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ChecksumAlgo crypt.HashType `json:"-"`
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}
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// EncodeTo serializes a Trix struct into the .trix binary format and writes it to an io.Writer.
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func EncodeTo(trix *Trix, magicNumber string, w io.Writer) error {
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// Encode serializes a Trix struct into the .trix binary format.
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func Encode(trix *Trix, magicNumber string) ([]byte, error) {
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if len(magicNumber) != 4 {
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return ErrMagicNumberLength
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return nil, ErrMagicNumberLength
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}
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// Calculate and add checksum if an algorithm is specified
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@ -49,57 +50,52 @@ func EncodeTo(trix *Trix, magicNumber string, w io.Writer) error {
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headerBytes, err := json.Marshal(trix.Header)
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if err != nil {
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return err
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return nil, err
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}
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headerLength := uint32(len(headerBytes))
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buf := new(bytes.Buffer)
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// Write Magic Number
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if _, err := io.WriteString(w, magicNumber); err != nil {
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return err
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if _, err := buf.WriteString(magicNumber); err != nil {
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return nil, err
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}
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// Write Version
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if _, err := w.Write([]byte{byte(Version)}); err != nil {
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return err
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if err := buf.WriteByte(byte(Version)); err != nil {
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return nil, err
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}
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// Write Header Length
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if err := binary.Write(w, binary.BigEndian, headerLength); err != nil {
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return err
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if err := binary.Write(buf, binary.BigEndian, headerLength); err != nil {
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return nil, err
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}
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// Write JSON Header
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if _, err := w.Write(headerBytes); err != nil {
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return err
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if _, err := buf.Write(headerBytes); err != nil {
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return nil, err
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}
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// Write Payload
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if _, err := w.Write(trix.Payload); err != nil {
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return err
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}
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return nil
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}
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// Encode serializes a Trix struct into the .trix binary format.
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func Encode(trix *Trix, magicNumber string) ([]byte, error) {
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var buf bytes.Buffer
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err := EncodeTo(trix, magicNumber, &buf)
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if err != nil {
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if _, err := buf.Write(trix.Payload); err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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// DecodeFrom deserializes the .trix binary format from an io.Reader into a Trix struct.
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func DecodeFrom(r io.Reader, magicNumber string) (*Trix, error) {
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// Decode deserializes the .trix binary format into a Trix struct.
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// Note: Sigils are not stored in the format and must be re-attached by the caller.
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func Decode(data []byte, magicNumber string) (*Trix, error) {
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if len(magicNumber) != 4 {
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return nil, ErrMagicNumberLength
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}
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buf := bytes.NewReader(data)
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// Read and Verify Magic Number
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magic := make([]byte, 4)
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if _, err := io.ReadFull(r, magic); err != nil {
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if _, err := io.ReadFull(buf, magic); err != nil {
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return nil, err
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}
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if string(magic) != magicNumber {
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@ -107,26 +103,28 @@ func DecodeFrom(r io.Reader, magicNumber string) (*Trix, error) {
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}
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// Read and Verify Version
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versionByte := make([]byte, 1)
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if _, err := io.ReadFull(r, versionByte); err != nil {
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version, err := buf.ReadByte()
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if err != nil {
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return nil, err
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}
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if versionByte[0] != Version {
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if version != Version {
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return nil, ErrInvalidVersion
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}
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// Read Header Length
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var headerLength uint32
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if err := binary.Read(r, binary.BigEndian, &headerLength); err != nil {
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if err := binary.Read(buf, binary.BigEndian, &headerLength); err != nil {
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return nil, err
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}
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// We can't implement the ErrInvalidHeaderLength check here because we don't know the total length of the stream.
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// The check is implicitly handled by io.ReadFull, which will return io.ErrUnexpectedEOF if the stream ends prematurely.
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// Sanity check the header length to prevent massive allocations.
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if headerLength > MaxHeaderSize {
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return nil, ErrHeaderTooLarge
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}
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// Read JSON Header
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headerBytes := make([]byte, headerLength)
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if _, err := io.ReadFull(r, headerBytes); err != nil {
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if _, err := io.ReadFull(buf, headerBytes); err != nil {
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return nil, err
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}
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var header map[string]interface{}
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@ -135,7 +133,7 @@ func DecodeFrom(r io.Reader, magicNumber string) (*Trix, error) {
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}
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// Read Payload
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payload, err := io.ReadAll(r)
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payload, err := io.ReadAll(buf)
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if err != nil {
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return nil, err
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}
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@ -158,26 +156,6 @@ func DecodeFrom(r io.Reader, magicNumber string) (*Trix, error) {
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}, nil
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}
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// Decode deserializes the .trix binary format into a Trix struct.
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// Note: Sigils are not stored in the format and must be re-attached by the caller.
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func Decode(data []byte, magicNumber string) (*Trix, error) {
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buf := bytes.NewReader(data)
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// We can perform the header length check here because we have the full byte slice.
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// We read the header length, check it, then pass the rest of the buffer to DecodeFrom.
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// This is a bit of a hack, but it's the only way to keep the check.
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// A better solution would be to have a separate DecodeBytes function.
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if len(data) > 9 { // 4 magic + 1 version + 4 header length
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headerLengthBytes := data[5:9]
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headerLength := binary.BigEndian.Uint32(headerLengthBytes)
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if int64(headerLength) > int64(len(data)-9) {
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return nil, ErrInvalidHeaderLength
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}
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}
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return DecodeFrom(buf, magicNumber)
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}
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// Pack applies the In method of all attached sigils to the payload.
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func (t *Trix) Pack() error {
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for _, sigilName := range t.InSigils {
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@ -1,9 +1,7 @@
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package trix
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"io"
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"reflect"
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"testing"
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@ -54,12 +52,6 @@ func TestTrixEncodeDecode_Bad(t *testing.T) {
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assert.EqualError(t, err, "trix: magic number must be 4 bytes long")
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})
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t.Run("InvalidVersion", func(t *testing.T) {
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buf := []byte("TRIX\x03\x00\x00\x00\x02{}" + "payload") // Version 3
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_, err := Decode(buf, "TRIX")
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assert.Equal(t, ErrInvalidVersion, err)
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})
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t.Run("MalformedHeaderJSON", func(t *testing.T) {
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// Create a Trix struct with a header that cannot be marshaled to JSON.
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header := map[string]interface{}{
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@ -88,7 +80,7 @@ func TestTrixEncodeDecode_Ugly(t *testing.T) {
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_, err := Decode(buf, magicNumber)
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assert.Error(t, err)
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assert.Equal(t, err, ErrInvalidHeaderLength)
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assert.Equal(t, err, io.ErrUnexpectedEOF)
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})
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t.Run("DataTooShort", func(t *testing.T) {
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@ -152,99 +144,8 @@ func TestPackUnpack_Bad(t *testing.T) {
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assert.Contains(t, err.Error(), "unknown sigil name")
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}
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func TestPackUnpack_Ugly(t *testing.T) {
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t.Run("NilPayload", func(t *testing.T) {
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trix := &Trix{
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Header: map[string]interface{}{},
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Payload: nil,
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InSigils: []string{"reverse"},
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}
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err := trix.Pack()
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assert.NoError(t, err)
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})
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}
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// --- Checksum Tests ---
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// --- Stream Tests ---
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// mockErrorWriter is an io.Writer that always returns an error.
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type mockErrorWriter struct{}
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func (w *mockErrorWriter) Write(p []byte) (n int, err error) {
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return 0, errors.New("mock writer error")
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}
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// mockErrorReader is an io.Reader that always returns an error.
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type mockErrorReader struct{}
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func (r *mockErrorReader) Read(p []byte) (n int, err error) {
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return 0, errors.New("mock reader error")
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}
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func TestStream_Good(t *testing.T) {
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trix := &Trix{
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Header: map[string]interface{}{"content_type": "text/plain"},
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Payload: []byte("hello world"),
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}
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magicNumber := "STRM"
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var buf bytes.Buffer
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err := EncodeTo(trix, magicNumber, &buf)
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assert.NoError(t, err)
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decoded, err := DecodeFrom(&buf, magicNumber)
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assert.NoError(t, err)
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assert.True(t, reflect.DeepEqual(trix.Header, decoded.Header))
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assert.Equal(t, trix.Payload, decoded.Payload)
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}
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func TestStream_Bad(t *testing.T) {
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t.Run("WriterError", func(t *testing.T) {
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trix := &Trix{Header: map[string]interface{}{}, Payload: []byte("payload")}
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err := EncodeTo(trix, "FAIL", &mockErrorWriter{})
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assert.Error(t, err)
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assert.EqualError(t, err, "mock writer error")
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})
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t.Run("ReaderError", func(t *testing.T) {
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_, err := DecodeFrom(&mockErrorReader{}, "FAIL")
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assert.Error(t, err)
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assert.EqualError(t, err, "mock reader error")
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})
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}
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func TestStream_Ugly(t *testing.T) {
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t.Run("EmptyReader", func(t *testing.T) {
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_, err := DecodeFrom(bytes.NewReader([]byte{}), "UGLY")
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assert.Error(t, err)
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})
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}
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func TestChecksum_Ugly(t *testing.T) {
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t.Run("MissingAlgoInHeader", func(t *testing.T) {
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header := `{"checksum":"5891b5b522d5df086d0ff0b110fbd9d21bb4fc7163af34d08286a2e846f6be03"}` // sha256 checksum for "hello world"
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payload := "hello world"
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magicNumber := "UGLY"
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var buf []byte
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buf = append(buf, []byte(magicNumber)...)
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buf = append(buf, byte(Version))
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headerLen := uint32(len(header))
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headerLenBytes := make([]byte, 4)
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binary.BigEndian.PutUint32(headerLenBytes, headerLen)
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buf = append(buf, headerLenBytes...)
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buf = append(buf, []byte(header)...)
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buf = append(buf, []byte(payload)...)
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_, err := Decode(buf, magicNumber)
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assert.Error(t, err)
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assert.Contains(t, err.Error(), "checksum algorithm not found in header")
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})
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}
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func TestChecksum_Good(t *testing.T) {
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trix := &Trix{
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Header: map[string]interface{}{},
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@ -276,3 +177,26 @@ func TestChecksum_Bad(t *testing.T) {
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assert.Equal(t, ErrChecksumMismatch, err)
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}
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func TestChecksum_Ugly(t *testing.T) {
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t.Run("MissingAlgoInHeader", func(t *testing.T) {
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trix := &Trix{
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Header: map[string]interface{}{},
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Payload: []byte("hello world"),
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ChecksumAlgo: crypt.SHA256,
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}
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encoded, err := Encode(trix, "UGLY")
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assert.NoError(t, err)
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// Manually decode to tamper with the header
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decoded, err := Decode(encoded, "UGLY")
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assert.NoError(t, err)
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delete(decoded.Header, "checksum_algo")
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// Re-encode with the tampered header
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tamperedEncoded, err := Encode(decoded, "UGLY")
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assert.NoError(t, err)
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_, err = Decode(tamperedEncoded, "UGLY")
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assert.Error(t, err)
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})
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}
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Add table
Reference in a new issue