prestodb/presto · critical · PrestoException

GENERIC_INTERNAL_ERROR

GENERIC_INTERNAL_ERROR

Error message

Encrypted data size is too small: %s. It must be at least the size of the initialization vector: %s.

What it means

AesSpillCipher.decrypt requires the encrypted buffer to start with an initialization vector of ivBytes length; if the remaining bytes are fewer than ivBytes the input is not a valid ciphertext produced by this cipher. It is surfaced as GENERIC_INTERNAL_ERROR because corrupt spill data is an internal invariant violation, not a user error.

Source

Thrown at presto-main-base/src/main/java/com/facebook/presto/spiller/AesSpillCipher.java:54

    //  256-bit AES CTR mode
    private static final String CIPHER_NAME = "AES/CTR/NoPadding";
    private static final int KEY_BITS = 256;

    private SecretKey key;
    private final int ivBytes;

    AesSpillCipher()
    {
        this.key = generateNewSecretKey();
        this.ivBytes = createEncryptCipher().getIV().length;
    }

    @Override
    public ByteBuffer decrypt(ByteBuffer encryptedData)
    {
        int length = encryptedData.remaining();
        if (length < ivBytes) {
            throw new PrestoException(GENERIC_INTERNAL_ERROR, format("Encrypted data size is too small: %s. It must be at least the size of the initialization vector: %s.", length, ivBytes));
        }
        byte[] iv = new byte[ivBytes];
        encryptedData.get(iv);
        Cipher cipher = createDecryptCipher(new IvParameterSpec(iv));
        ByteBuffer output = ByteBuffer.allocate(cipher.getOutputSize(encryptedData.remaining()));
        try {
            cipher.doFinal(encryptedData, output);
            ((Buffer) output).flip();
            return output;
        }
        catch (GeneralSecurityException e) {
            throw new PrestoException(GENERIC_INTERNAL_ERROR, "Cannot decrypt previously encrypted data: " + e.getMessage(), e);
        }
    }

    @Override
    public byte[] decrypt(byte[] encryptedData)
    {

View on GitHub (pinned to 55bb57d202)

Solutions

Verify spill encryption configuration matches between write and read paths (spiller cipher settings unchanged across restarts/versions)
Delete/recover the corrupted spill files and re-run the query
Check for disk-full or crash conditions that could truncate spill writes
Investigate reader code for offsets/alignment bugs that shrink the buffer below ivBytes

Example fix

// before
ByteBuffer decrypted = cipher.decrypt(possiblyTruncatedBuffer);
// after
if (encrypted.remaining() >= IV_LENGTH) {
    ByteBuffer decrypted = cipher.decrypt(encrypted);
} else {
    throw new IOException("Spill block truncated: " + encrypted.remaining() + " bytes");
}

Defensive patterns

Strategy: validation

Validate before calling

if (encryptedData == null || encryptedData.remaining() < IV_LENGTH_BYTES) {
    throw new IOException("Spill block too small to contain IV: "
        + (encryptedData == null ? 0 : encryptedData.remaining()) + " bytes");
}

Type guard

boolean isPlausibleCiphertext(ByteBuffer buffer) {
    return buffer != null && buffer.remaining() >= IV_LENGTH_BYTES;
}

Try / catch

try {
    ByteBuffer plain = cipher.decrypt(encrypted);
} catch (PrestoException e) {
    if (e.getErrorCode().toCode() == GENERIC_INTERNAL_ERROR.toCode()
            && e.getMessage().contains("too small")) {
        // treat spill block as corrupt: discard and recompute/re-read source
    }
}

Prevention

Never disable spill encryption on some nodes only — keep config uniform across the cluster
Clean stale spill directories after crash or version upgrades
Monitor disk usage to avoid truncated writes
Persist a marker/length header with encrypted blocks so readers can detect truncation

When it happens

Trigger: Calling decrypt(ByteBuffer) with a buffer containing fewer than ivBytes bytes — e.g. a truncated, empty, or plaintext (never-encrypted) spill file being read as encrypted data, or an offset/read bug that misaligns the buffer.

Common situations: Spill files truncated by disk-full or premature cleanup; mismatched spill encryption configuration (data written unencrypted but read with an AesSpillCipher, or vice versa); partially written files after a crash; memory/disk corruption.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/6b09211d2ee54785. Report an issue: GitHub.