diff --git a/accounts/abi/unpack.go b/accounts/abi/unpack.go index 334245661..51fb9ab9b 100644 --- a/accounts/abi/unpack.go +++ b/accounts/abi/unpack.go @@ -95,6 +95,9 @@ func readFixedBytes(t Type, word []byte) (interface{}, error) { // iteratively unpack elements func forEachUnpack(t Type, output []byte, start, size int) (interface{}, error) { + if size < 0 { + return nil, fmt.Errorf("cannot marshal input to array, size is negative (%d)", size) + } if start+32*size > len(output) { return nil, fmt.Errorf("abi: cannot marshal in to go array: offset %d would go over slice boundary (len=%d)", len(output), start+32*size) } @@ -181,16 +184,22 @@ func toGoType(index int, t Type, output []byte) (interface{}, error) { // interprets a 32 byte slice as an offset and then determines which indice to look to decode the type. func lengthPrefixPointsTo(index int, output []byte) (start int, length int, err error) { - offset := int(binary.BigEndian.Uint64(output[index+24 : index+32])) + offsetBig := big.NewInt(0).SetBytes(output[index : index+32]) + if !offsetBig.IsInt64() { + return 0, 0, fmt.Errorf("abi offset larger than int64: %v", offsetBig) + } + offset := int(offsetBig.Int64()) if offset+32 > len(output) { return 0, 0, fmt.Errorf("abi: cannot marshal in to go slice: offset %d would go over slice boundary (len=%d)", len(output), offset+32) } - length = int(binary.BigEndian.Uint64(output[offset+24 : offset+32])) + lengthBig := big.NewInt(0).SetBytes(output[offset : offset+32]) + if !lengthBig.IsInt64() { + return 0, 0, fmt.Errorf("abi length larger than int64: %v", lengthBig) + } + length = int(lengthBig.Int64()) if offset+32+length > len(output) { return 0, 0, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32+length) } start = offset + 32 - - //fmt.Printf("LENGTH PREFIX INFO: \nsize: %v\noffset: %v\nstart: %v\n", length, offset, start) return } diff --git a/accounts/abi/unpack_test.go b/accounts/abi/unpack_test.go index e9f910812..742211244 100644 --- a/accounts/abi/unpack_test.go +++ b/accounts/abi/unpack_test.go @@ -683,3 +683,73 @@ func TestUnmarshal(t *testing.T) { t.Fatal("expected error:", err) } } + +func TestOOMMaliciousInput(t *testing.T) { + oomTests := []unpackTest{ + { + def: `[{"type": "uint8[]"}]`, + enc: "0000000000000000000000000000000000000000000000000000000000000020" + // offset + "0000000000000000000000000000000000000000000000000000000000000003" + // num elems + "0000000000000000000000000000000000000000000000000000000000000001" + // elem 1 + "0000000000000000000000000000000000000000000000000000000000000002", // elem 2 + }, + { // Length larger than 64 bits + def: `[{"type": "uint8[]"}]`, + enc: "0000000000000000000000000000000000000000000000000000000000000020" + // offset + "00ffffffffffffffffffffffffffffffffffffffffffffff0000000000000002" + // num elems + "0000000000000000000000000000000000000000000000000000000000000001" + // elem 1 + "0000000000000000000000000000000000000000000000000000000000000002", // elem 2 + }, + { // Offset very large (over 64 bits) + def: `[{"type": "uint8[]"}]`, + enc: "00ffffffffffffffffffffffffffffffffffffffffffffff0000000000000020" + // offset + "0000000000000000000000000000000000000000000000000000000000000002" + // num elems + "0000000000000000000000000000000000000000000000000000000000000001" + // elem 1 + "0000000000000000000000000000000000000000000000000000000000000002", // elem 2 + }, + { // Offset very large (below 64 bits) + def: `[{"type": "uint8[]"}]`, + enc: "0000000000000000000000000000000000000000000000007ffffffffff00020" + // offset + "0000000000000000000000000000000000000000000000000000000000000002" + // num elems + "0000000000000000000000000000000000000000000000000000000000000001" + // elem 1 + "0000000000000000000000000000000000000000000000000000000000000002", // elem 2 + }, + { // Offset negative (as 64 bit) + def: `[{"type": "uint8[]"}]`, + enc: "000000000000000000000000000000000000000000000000f000000000000020" + // offset + "0000000000000000000000000000000000000000000000000000000000000002" + // num elems + "0000000000000000000000000000000000000000000000000000000000000001" + // elem 1 + "0000000000000000000000000000000000000000000000000000000000000002", // elem 2 + }, + + { // Negative length + def: `[{"type": "uint8[]"}]`, + enc: "0000000000000000000000000000000000000000000000000000000000000020" + // offset + "000000000000000000000000000000000000000000000000f000000000000002" + // num elems + "0000000000000000000000000000000000000000000000000000000000000001" + // elem 1 + "0000000000000000000000000000000000000000000000000000000000000002", // elem 2 + }, + { // Very large length + def: `[{"type": "uint8[]"}]`, + enc: "0000000000000000000000000000000000000000000000000000000000000020" + // offset + "0000000000000000000000000000000000000000000000007fffffffff000002" + // num elems + "0000000000000000000000000000000000000000000000000000000000000001" + // elem 1 + "0000000000000000000000000000000000000000000000000000000000000002", // elem 2 + }, + } + for i, test := range oomTests { + def := fmt.Sprintf(`[{ "name" : "method", "outputs": %s}]`, test.def) + abi, err := JSON(strings.NewReader(def)) + if err != nil { + t.Fatalf("invalid ABI definition %s: %v", def, err) + } + encb, err := hex.DecodeString(test.enc) + if err != nil { + t.Fatalf("invalid hex: %s" + test.enc) + } + _, err = abi.Methods["method"].Outputs.UnpackValues(encb) + if err == nil { + t.Fatalf("Expected error on malicious input, test %d", i) + } + } +}