apacheGH-43946: [C++][Parquet] Guard against use of cleared decryptor…

…/encryptor (apache#43947)

This is to get a clearer error rather than an obscure crash, see apache#43057 for an example.

* GitHub Issue: apache#43946

Authored-by: Antoine Pitrou <antoine@python.org>
Signed-off-by: Antoine Pitrou <antoine@python.org>

cpp/src/parquet/encryption/encryption_internal.cc

@@ -89,6 +89,12 @@ class AesEncryptor::AesEncryptorImpl {
   }
 
  private:
+  void CheckValid() const {
+    if (ctx_ == nullptr) {
+      throw ParquetException("AesEncryptor was wiped out");
+    }
+  }
+
   EVP_CIPHER_CTX* ctx_;
   int32_t aes_mode_;
   int32_t key_length_;
@@ -156,6 +162,8 @@ AesEncryptor::AesEncryptorImpl::AesEncryptorImpl(ParquetCipher::type alg_id,
 int32_t AesEncryptor::AesEncryptorImpl::SignedFooterEncrypt(
     span<const uint8_t> footer, span<const uint8_t> key, span<const uint8_t> aad,
     span<const uint8_t> nonce, span<uint8_t> encrypted_footer) {
+  CheckValid();
+
   if (static_cast<size_t>(key_length_) != key.size()) {
     std::stringstream ss;
     ss << "Wrong key length " << key.size() << ". Should be " << key_length_;
@@ -180,6 +188,8 @@ int32_t AesEncryptor::AesEncryptorImpl::Encrypt(span<const uint8_t> plaintext,
                                                 span<const uint8_t> key,
                                                 span<const uint8_t> aad,
                                                 span<uint8_t> ciphertext) {
+  CheckValid();
+
   if (static_cast<size_t>(key_length_) != key.size()) {
     std::stringstream ss;
     ss << "Wrong key length " << key.size() << ". Should be " << key_length_;
@@ -413,6 +423,12 @@ class AesDecryptor::AesDecryptorImpl {
   }
 
  private:
+  void CheckValid() const {
+    if (ctx_ == nullptr) {
+      throw ParquetException("AesDecryptor was wiped out");
+    }
+  }
+
   EVP_CIPHER_CTX* ctx_;
   int32_t aes_mode_;
   int32_t key_length_;
@@ -714,6 +730,8 @@ int32_t AesDecryptor::AesDecryptorImpl::Decrypt(span<const uint8_t> ciphertext,
                                                 span<const uint8_t> key,
                                                 span<const uint8_t> aad,
                                                 span<uint8_t> plaintext) {
+  CheckValid();
+
   if (static_cast<size_t>(key_length_) != key.size()) {
     std::stringstream ss;
     ss << "Wrong key length " << key.size() << ". Should be " << key_length_;
@@ -806,4 +824,7 @@ void RandBytes(unsigned char* buf, size_t num) {
 
 void EnsureBackendInitialized() { openssl::EnsureInitialized(); }
 
+#undef ENCRYPT_INIT
+#undef DECRYPT_INIT
+
 }  // namespace parquet::encryption