src: fix memory leaks and refactor `ByteSource`

Add ByteSource::Builder to replace the common MallocOpenSSL() +
ByteSource::Allocated() pattern.

Remove ByteSource::reset() that is unused.

Remove ByteSource::Resize() to make ByteSource truly immutable (until
moved away). Instead, ByteSource::Builder::release() takes an optional
size argument that truncates the resulting ByteSource.

Fix occurrences of MallocOpenSSL() that do not always free the allocated
memory by using the new ByteSource::Builder class instead.

Remove ByteSource::get() and replace uses with ByteSource::data().

Remove ReallocOpenSSL() because it likely only saves us a few bytes
whenever we use it.

PR-URL: https://github.com/nodejs/node/pull/43202
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

16 files changed, 255 insertions, 335 deletions

diff --git a/src/crypto/crypto_aes.cc b/src/crypto/crypto_aes.cc
index 76d3e385345..5f84e21fc23 100644
--- a/src/crypto/crypto_aes.cc
+++ b/src/crypto/crypto_aes.cc
@@ -89,11 +89,10 @@ WebCryptoCipherStatus AES_Cipher(
       case kWebCryptoCipherDecrypt:
         // If in decrypt mode, the auth tag must be set in the params.tag.
         CHECK(params.tag);
-        if (!EVP_CIPHER_CTX_ctrl(
-                ctx.get(),
-                EVP_CTRL_AEAD_SET_TAG,
-                params.tag.size(),
-                const_cast<char*>(params.tag.get()))) {
+        if (!EVP_CIPHER_CTX_ctrl(ctx.get(),
+                                 EVP_CTRL_AEAD_SET_TAG,
+                                 params.tag.size(),
+                                 const_cast<char*>(params.tag.data<char>()))) {
           return WebCryptoCipherStatus::FAILED;
         }
         break;
@@ -125,9 +124,7 @@ WebCryptoCipherStatus AES_Cipher(
     return WebCryptoCipherStatus::FAILED;
   }
 
-  char* data = MallocOpenSSL<char>(buf_len);
-  ByteSource buf = ByteSource::Allocated(data, buf_len);
-  unsigned char* ptr = reinterpret_cast<unsigned char*>(data);
+  ByteSource::Builder buf(buf_len);
 
   // In some outdated version of OpenSSL (e.g.
   // ubi81_sharedlibs_openssl111fips_x64) may be used in sharedlib mode, the
@@ -139,20 +136,19 @@ WebCryptoCipherStatus AES_Cipher(
   // Refs: https://github.com/nodejs/node/pull/38913#issuecomment-866505244
   if (in.size() == 0) {
     out_len = 0;
-  } else if (!EVP_CipherUpdate(
-          ctx.get(),
-          ptr,
-          &out_len,
-          in.data<unsigned char>(),
-          in.size())) {
+  } else if (!EVP_CipherUpdate(ctx.get(),
+                               buf.data<unsigned char>(),
+                               &out_len,
+                               in.data<unsigned char>(),
+                               in.size())) {
     return WebCryptoCipherStatus::FAILED;
   }
 
   total += out_len;
   CHECK_LE(out_len, buf_len);
-  ptr += out_len;
   out_len = EVP_CIPHER_CTX_block_size(ctx.get());
-  if (!EVP_CipherFinal_ex(ctx.get(), ptr, &out_len)) {
+  if (!EVP_CipherFinal_ex(
+          ctx.get(), buf.data<unsigned char>() + total, &out_len)) {
     return WebCryptoCipherStatus::FAILED;
   }
   total += out_len;
@@ -160,15 +156,16 @@ WebCryptoCipherStatus AES_Cipher(
   // If using AES_GCM, grab the generated auth tag and append
   // it to the end of the ciphertext.
   if (cipher_mode == kWebCryptoCipherEncrypt && mode == EVP_CIPH_GCM_MODE) {
-    data += out_len;
-    if (!EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_AEAD_GET_TAG, tag_len, ptr))
+    if (!EVP_CIPHER_CTX_ctrl(ctx.get(),
+                             EVP_CTRL_AEAD_GET_TAG,
+                             tag_len,
+                             buf.data<unsigned char>() + total))
       return WebCryptoCipherStatus::FAILED;
     total += tag_len;
   }
 
   // It's possible that we haven't used the full allocated space. Size down.
-  buf.Resize(total);
-  *out = std::move(buf);
+  *out = std::move(buf).release(total);
 
   return WebCryptoCipherStatus::OK;
 }
@@ -295,24 +292,20 @@ WebCryptoCipherStatus AES_CTR_Cipher(
     return WebCryptoCipherStatus::FAILED;
   }
 
-  // Output size is identical to the input size
-  char* data = MallocOpenSSL<char>(in.size());
-  ByteSource buf = ByteSource::Allocated(data, in.size());
-  unsigned char* ptr = reinterpret_cast<unsigned char*>(data);
+  // Output size is identical to the input size.
+  ByteSource::Builder buf(in.size());
 
   // Also just like in chromium's implementation, if we can process
   // the input without wrapping the counter, we'll do it as a single
   // call here. If we can't, we'll fallback to the a two-step approach
   if (BN_cmp(remaining_until_reset.get(), num_output.get()) >= 0) {
-    auto status = AES_CTR_Cipher2(
-        key_data,
-        cipher_mode,
-        params,
-        in,
-        params.iv.data<unsigned char>(),
-        ptr);
-    if (status == WebCryptoCipherStatus::OK)
-      *out = std::move(buf);
+    auto status = AES_CTR_Cipher2(key_data,
+                                  cipher_mode,
+                                  params,
+                                  in,
+                                  params.iv.data<unsigned char>(),
+                                  buf.data<unsigned char>());
+    if (status == WebCryptoCipherStatus::OK) *out = std::move(buf).release();
     return status;
   }
 
@@ -320,13 +313,13 @@ WebCryptoCipherStatus AES_CTR_Cipher(
   BN_ULONG input_size_part1 = blocks_part1 * kAesBlockSize;
 
   // Encrypt the first part...
-  auto status = AES_CTR_Cipher2(
-      key_data,
-      cipher_mode,
-      params,
-      ByteSource::Foreign(in.get(), input_size_part1),
-      params.iv.data<unsigned char>(),
-      ptr);
+  auto status =
+      AES_CTR_Cipher2(key_data,
+                      cipher_mode,
+                      params,
+                      ByteSource::Foreign(in.data<char>(), input_size_part1),
+                      params.iv.data<unsigned char>(),
+                      buf.data<unsigned char>());
 
   if (status != WebCryptoCipherStatus::OK)
     return status;
@@ -335,18 +328,16 @@ WebCryptoCipherStatus AES_CTR_Cipher(
   std::vector<unsigned char> new_counter_block = BlockWithZeroedCounter(params);
 
   // Encrypt the second part...
-  status = AES_CTR_Cipher2(
-      key_data,
-      cipher_mode,
-      params,
-      ByteSource::Foreign(
-          in.get() + input_size_part1,
-          in.size() - input_size_part1),
-      new_counter_block.data(),
-      ptr + input_size_part1);
-
-  if (status == WebCryptoCipherStatus::OK)
-    *out = std::move(buf);
+  status =
+      AES_CTR_Cipher2(key_data,
+                      cipher_mode,
+                      params,
+                      ByteSource::Foreign(in.data<char>() + input_size_part1,
+                                          in.size() - input_size_part1),
+                      new_counter_block.data(),
+                      buf.data<unsigned char>() + input_size_part1);
+
+  if (status == WebCryptoCipherStatus::OK) *out = std::move(buf).release();
 
   return status;
 }
diff --git a/src/crypto/crypto_common.cc b/src/crypto/crypto_common.cc
index 0b172e40ee7..3341859e04c 100644
--- a/src/crypto/crypto_common.cc
+++ b/src/crypto/crypto_common.cc
@@ -525,8 +525,7 @@ MaybeLocal<Value> GetSerialNumber(Environment* env, X509* cert) {
     if (bn) {
       char* data = BN_bn2hex(bn.get());
       ByteSource buf = ByteSource::Allocated(data, strlen(data));
-      if (buf)
-        return OneByteString(env->isolate(), buf.get());
+      if (buf) return OneByteString(env->isolate(), buf.data<unsigned char>());
     }
   }
 
diff --git a/src/crypto/crypto_dh.cc b/src/crypto/crypto_dh.cc
index ab4fc0f6e24..faadb97fa4c 100644
--- a/src/crypto/crypto_dh.cc
+++ b/src/crypto/crypto_dh.cc
@@ -606,18 +606,13 @@ ByteSource StatelessDiffieHellmanThreadsafe(
       EVP_PKEY_derive(ctx.get(), nullptr, &out_size) <= 0)
     return ByteSource();
 
-  char* buf = MallocOpenSSL<char>(out_size);
-  ByteSource out = ByteSource::Allocated(buf, out_size);
-
-  if (EVP_PKEY_derive(
-          ctx.get(),
-          reinterpret_cast<unsigned char*>(buf),
-          &out_size) <= 0) {
+  ByteSource::Builder out(out_size);
+  if (EVP_PKEY_derive(ctx.get(), out.data<unsigned char>(), &out_size) <= 0) {
     return ByteSource();
   }
 
-  ZeroPadDiffieHellmanSecret(out_size, buf, out.size());
-  return out;
+  ZeroPadDiffieHellmanSecret(out_size, out.data<char>(), out.size());
+  return std::move(out).release();
 }
 }  // namespace
 
diff --git a/src/crypto/crypto_ec.cc b/src/crypto/crypto_ec.cc
index e9fe65ffd57..e6a90200a43 100644
--- a/src/crypto/crypto_ec.cc
+++ b/src/crypto/crypto_ec.cc
@@ -486,12 +486,9 @@ Maybe<bool> ECDHBitsTraits::AdditionalConfig(
   return Just(true);
 }
 
-bool ECDHBitsTraits::DeriveBits(
-    Environment* env,
-    const ECDHBitsConfig& params,
-    ByteSource* out) {
-
-  char* data = nullptr;
+bool ECDHBitsTraits::DeriveBits(Environment* env,
+                                const ECDHBitsConfig& params,
+                                ByteSource* out) {
   size_t len = 0;
   ManagedEVPPKey m_privkey = params.private_->GetAsymmetricKey();
   ManagedEVPPKey m_pubkey = params.public_->GetAsymmetricKey();
@@ -513,15 +510,14 @@ bool ECDHBitsTraits::DeriveBits(
         return false;
       }
 
-      data = MallocOpenSSL<char>(len);
+      ByteSource::Builder buf(len);
 
-      if (EVP_PKEY_derive(
-              ctx.get(),
-              reinterpret_cast<unsigned char*>(data),
-              &len) <= 0) {
+      if (EVP_PKEY_derive(ctx.get(), buf.data<unsigned char>(), &len) <= 0) {
         return false;
       }
 
+      *out = std::move(buf).release(len);
+
       break;
     }
     default: {
@@ -543,22 +539,18 @@ bool ECDHBitsTraits::DeriveBits(
       const EC_POINT* pub = EC_KEY_get0_public_key(public_key);
       int field_size = EC_GROUP_get_degree(group);
       len = (field_size + 7) / 8;
-      data = MallocOpenSSL<char>(len);
-      CHECK_NOT_NULL(data);
+      ByteSource::Builder buf(len);
       CHECK_NOT_NULL(pub);
       CHECK_NOT_NULL(private_key);
-      if (ECDH_compute_key(
-              data,
-              len,
-              pub,
-              private_key,
-              nullptr) <= 0) {
+      if (ECDH_compute_key(buf.data<char>(), len, pub, private_key, nullptr) <=
+          0) {
         return false;
       }
+
+      *out = std::move(buf).release();
     }
   }
-  ByteSource buf = ByteSource::Allocated(data, len);
-  *out = std::move(buf);
+
   return true;
 }
 
@@ -646,7 +638,6 @@ WebCryptoKeyExportStatus EC_Raw_Export(
 
   const EC_KEY* ec_key = EVP_PKEY_get0_EC_KEY(m_pkey.get());
 
-  unsigned char* data;
   size_t len = 0;
 
   if (ec_key == nullptr) {
@@ -666,9 +657,10 @@ WebCryptoKeyExportStatus EC_Raw_Export(
     // Get the size of the raw key data
     if (fn(m_pkey.get(), nullptr, &len) == 0)
       return WebCryptoKeyExportStatus::INVALID_KEY_TYPE;
-    data = MallocOpenSSL<unsigned char>(len);
-    if (fn(m_pkey.get(), data, &len) == 0)
+    ByteSource::Builder data(len);
+    if (fn(m_pkey.get(), data.data<unsigned char>(), &len) == 0)
       return WebCryptoKeyExportStatus::INVALID_KEY_TYPE;
+    *out = std::move(data).release(len);
   } else {
     if (key_data->GetKeyType() != kKeyTypePublic)
       return WebCryptoKeyExportStatus::INVALID_KEY_TYPE;
@@ -680,17 +672,16 @@ WebCryptoKeyExportStatus EC_Raw_Export(
     len = EC_POINT_point2oct(group, point, form, nullptr, 0, nullptr);
     if (len == 0)
       return WebCryptoKeyExportStatus::FAILED;
-    data = MallocOpenSSL<unsigned char>(len);
-    size_t check_len =
-        EC_POINT_point2oct(group, point, form, data, len, nullptr);
+    ByteSource::Builder data(len);
+    size_t check_len = EC_POINT_point2oct(
+        group, point, form, data.data<unsigned char>(), len, nullptr);
     if (check_len == 0)
       return WebCryptoKeyExportStatus::FAILED;
 
     CHECK_EQ(len, check_len);
+    *out = std::move(data).release();
   }
 
-  *out = ByteSource::Allocated(reinterpret_cast<char*>(data), len);
-
   return WebCryptoKeyExportStatus::OK;
 }
 }  // namespace
@@ -853,38 +844,27 @@ Maybe<bool> ExportJWKEdKey(
   if (!EVP_PKEY_get_raw_public_key(pkey.get(), nullptr, &len))
     return Nothing<bool>();
 
-  unsigned char* data = MallocOpenSSL<unsigned char>(len);
-  ByteSource out = ByteSource::Allocated(reinterpret_cast<char*>(data), len);
+  ByteSource::Builder out(len);
 
   if (key->GetKeyType() == kKeyTypePrivate) {
-    if (!EVP_PKEY_get_raw_private_key(pkey.get(), data, &len) ||
+    if (!EVP_PKEY_get_raw_private_key(
+            pkey.get(), out.data<unsigned char>(), &len) ||
         !StringBytes::Encode(
-            env->isolate(),
-            reinterpret_cast<const char*>(data),
-            len,
-            BASE64URL,
-            &error).ToLocal(&encoded) ||
-        !target->Set(
-            env->context(),
-            env->jwk_d_string(),
-            encoded).IsJust()) {
+             env->isolate(), out.data<const char>(), len, BASE64URL, &error)
+             .ToLocal(&encoded) ||
+        !target->Set(env->context(), env->jwk_d_string(), encoded).IsJust()) {
       if (!error.IsEmpty())
         env->isolate()->ThrowException(error);
       return Nothing<bool>();
     }
   }
 
-  if (!EVP_PKEY_get_raw_public_key(pkey.get(), data, &len) ||
+  if (!EVP_PKEY_get_raw_public_key(
+          pkey.get(), out.data<unsigned char>(), &len) ||
       !StringBytes::Encode(
-          env->isolate(),
-          reinterpret_cast<const char*>(data),
-          len,
-          BASE64URL,
-          &error).ToLocal(&encoded) ||
-      !target->Set(
-          env->context(),
-          env->jwk_x_string(),
-          encoded).IsJust()) {
+           env->isolate(), out.data<const char>(), len, BASE64URL, &error)
+           .ToLocal(&encoded) ||
+      !target->Set(env->context(), env->jwk_x_string(), encoded).IsJust()) {
     if (!error.IsEmpty())
       env->isolate()->ThrowException(error);
     return Nothing<bool>();
diff --git a/src/crypto/crypto_hash.cc b/src/crypto/crypto_hash.cc
index 8f7128569c7..24dc436d248 100644
--- a/src/crypto/crypto_hash.cc
+++ b/src/crypto/crypto_hash.cc
@@ -171,38 +171,29 @@ void Hash::HashDigest(const FunctionCallbackInfo<Value>& args) {
     // so we need to cache it.
     // See https://github.com/nodejs/node/issues/28245.
 
-    char* md_value = MallocOpenSSL<char>(len);
-    ByteSource digest = ByteSource::Allocated(md_value, len);
+    ByteSource::Builder digest(len);
 
     size_t default_len = EVP_MD_CTX_size(hash->mdctx_.get());
     int ret;
     if (len == default_len) {
       ret = EVP_DigestFinal_ex(
-          hash->mdctx_.get(),
-          reinterpret_cast<unsigned char*>(md_value),
-          &len);
+          hash->mdctx_.get(), digest.data<unsigned char>(), &len);
       // The output length should always equal hash->md_len_
       CHECK_EQ(len, hash->md_len_);
     } else {
       ret = EVP_DigestFinalXOF(
-          hash->mdctx_.get(),
-          reinterpret_cast<unsigned char*>(md_value),
-          len);
+          hash->mdctx_.get(), digest.data<unsigned char>(), len);
     }
 
     if (ret != 1)
       return ThrowCryptoError(env, ERR_get_error());
 
-    hash->digest_ = std::move(digest);
+    hash->digest_ = std::move(digest).release();
   }
 
   Local<Value> error;
-  MaybeLocal<Value> rc =
-      StringBytes::Encode(env->isolate(),
-                          hash->digest_.get(),
-                          len,
-                          encoding,
-                          &error);
+  MaybeLocal<Value> rc = StringBytes::Encode(
+      env->isolate(), hash->digest_.data<char>(), len, encoding, &error);
   if (rc.IsEmpty()) {
     CHECK(!error.IsEmpty());
     env->isolate()->ThrowException(error);
@@ -291,28 +282,25 @@ bool HashTraits::DeriveBits(
   if (UNLIKELY(!ctx ||
                EVP_DigestInit_ex(ctx.get(), params.digest, nullptr) <= 0 ||
                EVP_DigestUpdate(
-                   ctx.get(),
-                   params.in.get(),
-                   params.in.size()) <= 0)) {
+                   ctx.get(), params.in.data<char>(), params.in.size()) <= 0)) {
     return false;
   }
 
   if (LIKELY(params.length > 0)) {
     unsigned int length = params.length;
-    char* data = MallocOpenSSL<char>(length);
-    ByteSource buf = ByteSource::Allocated(data, length);
-    unsigned char* ptr = reinterpret_cast<unsigned char*>(data);
+    ByteSource::Builder buf(length);
 
     size_t expected = EVP_MD_CTX_size(ctx.get());
 
-    int ret = (length == expected)
-        ? EVP_DigestFinal_ex(ctx.get(), ptr, &length)
-        : EVP_DigestFinalXOF(ctx.get(), ptr, length);
+    int ret =
+        (length == expected)
+            ? EVP_DigestFinal_ex(ctx.get(), buf.data<unsigned char>(), &length)
+            : EVP_DigestFinalXOF(ctx.get(), buf.data<unsigned char>(), length);
 
     if (UNLIKELY(ret != 1))
       return false;
 
-    *out = std::move(buf);
+    *out = std::move(buf).release();
   }
 
   return true;
diff --git a/src/crypto/crypto_hkdf.cc b/src/crypto/crypto_hkdf.cc
index b1efcbe55fa..79a84c12f55 100644
--- a/src/crypto/crypto_hkdf.cc
+++ b/src/crypto/crypto_hkdf.cc
@@ -102,34 +102,27 @@ bool HKDFTraits::DeriveBits(
     ByteSource* out) {
   EVPKeyCtxPointer ctx =
       EVPKeyCtxPointer(EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, nullptr));
-  if (!ctx ||
-      !EVP_PKEY_derive_init(ctx.get()) ||
-      !EVP_PKEY_CTX_hkdf_mode(
-        ctx.get(), EVP_PKEY_HKDEF_MODE_EXTRACT_AND_EXPAND) ||
+  if (!ctx || !EVP_PKEY_derive_init(ctx.get()) ||
+      !EVP_PKEY_CTX_hkdf_mode(ctx.get(),
+                              EVP_PKEY_HKDEF_MODE_EXTRACT_AND_EXPAND) ||
       !EVP_PKEY_CTX_set_hkdf_md(ctx.get(), params.digest) ||
       !EVP_PKEY_CTX_set1_hkdf_salt(
-        ctx.get(),
-        reinterpret_cast<const unsigned char*>(params.salt.get()),
-        params.salt.size()) ||
+          ctx.get(), params.salt.data<unsigned char>(), params.salt.size()) ||
       !EVP_PKEY_CTX_set1_hkdf_key(
-        ctx.get(),
-        reinterpret_cast<const unsigned char*>(params.key->GetSymmetricKey()),
-        params.key->GetSymmetricKeySize()) ||
+          ctx.get(),
+          reinterpret_cast<const unsigned char*>(params.key->GetSymmetricKey()),
+          params.key->GetSymmetricKeySize()) ||
       !EVP_PKEY_CTX_add1_hkdf_info(
-        ctx.get(),
-        reinterpret_cast<const unsigned char*>(params.info.get()),
-        params.info.size())) {
+          ctx.get(), params.info.data<unsigned char>(), params.info.size())) {
     return false;
   }
 
   size_t length = params.length;
-  char* data = MallocOpenSSL<char>(length);
-  ByteSource buf = ByteSource::Allocated(data, length);
-  unsigned char* ptr = reinterpret_cast<unsigned char*>(data);
-  if (EVP_PKEY_derive(ctx.get(), ptr, &length) <= 0)
+  ByteSource::Builder buf(length);
+  if (EVP_PKEY_derive(ctx.get(), buf.data<unsigned char>(), &length) <= 0)
     return false;
 
-  *out = std::move(buf);
+  *out = std::move(buf).release();
   return true;
 }
 
diff --git a/src/crypto/crypto_hmac.cc b/src/crypto/crypto_hmac.cc
index 296ae541a3e..afda92265e8 100644
--- a/src/crypto/crypto_hmac.cc
+++ b/src/crypto/crypto_hmac.cc
@@ -88,7 +88,7 @@ void Hmac::HmacInit(const FunctionCallbackInfo<Value>& args) {
 
   const node::Utf8Value hash_type(env->isolate(), args[0]);
   ByteSource key = ByteSource::FromSecretKeyBytes(env, args[1]);
-  hmac->HmacInit(*hash_type, key.get(), key.size());
+  hmac->HmacInit(*hash_type, key.data<char>(), key.size());
 }
 
 bool Hmac::HmacUpdate(const char* data, size_t len) {
@@ -241,17 +241,14 @@ bool HmacTraits::DeriveBits(
     return false;
   }
 
-  char* data = MallocOpenSSL<char>(EVP_MAX_MD_SIZE);
-  ByteSource buf = ByteSource::Allocated(data, EVP_MAX_MD_SIZE);
-  unsigned char* ptr = reinterpret_cast<unsigned char*>(data);
+  ByteSource::Builder buf(EVP_MAX_MD_SIZE);
   unsigned int len;
 
-  if (!HMAC_Final(ctx.get(), ptr, &len)) {
+  if (!HMAC_Final(ctx.get(), buf.data<unsigned char>(), &len)) {
     return false;
   }
 
-  buf.Resize(len);
-  *out = std::move(buf);
+  *out = std::move(buf).release(len);
 
   return true;
 }
@@ -267,9 +264,8 @@ Maybe<bool> HmacTraits::EncodeOutput(
       break;
     case SignConfiguration::kVerify:
       *result =
-          out->size() > 0 &&
-          out->size() == params.signature.size() &&
-          memcmp(out->get(), params.signature.get(), out->size()) == 0
+          out->size() > 0 && out->size() == params.signature.size() &&
+                  memcmp(out->data(), params.signature.data(), out->size()) == 0
               ? v8::True(env->isolate())
               : v8::False(env->isolate());
       break;
diff --git a/src/crypto/crypto_keys.cc b/src/crypto/crypto_keys.cc
index 5dd04edfbfa..ba37f24c48d 100644
--- a/src/crypto/crypto_keys.cc
+++ b/src/crypto/crypto_keys.cc
@@ -305,7 +305,7 @@ MaybeLocal<Value> WritePrivateKey(
   char* pass = nullptr;
   size_t pass_len = 0;
   if (!config.passphrase_.IsEmpty()) {
-    pass = const_cast<char*>(config.passphrase_->get());
+    pass = const_cast<char*>(config.passphrase_->data<char>());
     pass_len = config.passphrase_->size();
     if (pass == nullptr) {
       // OpenSSL will not actually dereference this pointer, so it can be any
@@ -744,7 +744,7 @@ ManagedEVPPKey ManagedEVPPKey::GetPrivateKeyFromJs(
 
     EVPKeyPointer pkey;
     ParseKeyResult ret =
-        ParsePrivateKey(&pkey, config.Release(), key.get(), key.size());
+        ParsePrivateKey(&pkey, config.Release(), key.data<char>(), key.size());
     return GetParsedKey(env, std::move(pkey), ret,
                         "Failed to read private key");
   } else {
@@ -893,7 +893,7 @@ ManagedEVPPKey KeyObjectData::GetAsymmetricKey() const {
 
 const char* KeyObjectData::GetSymmetricKey() const {
   CHECK_EQ(key_type_, kKeyTypeSecret);
-  return symmetric_key_.get();
+  return symmetric_key_.data<char>();
 }
 
 size_t KeyObjectData::GetSymmetricKeySize() const {
diff --git a/src/crypto/crypto_pbkdf2.cc b/src/crypto/crypto_pbkdf2.cc
index 345c7fe5ce6..963d0db6c62 100644
--- a/src/crypto/crypto_pbkdf2.cc
+++ b/src/crypto/crypto_pbkdf2.cc
@@ -115,26 +115,23 @@ bool PBKDF2Traits::DeriveBits(
     Environment* env,
     const PBKDF2Config& params,
     ByteSource* out) {
-  char* data = MallocOpenSSL<char>(params.length);
-  ByteSource buf = ByteSource::Allocated(data, params.length);
-  unsigned char* ptr = reinterpret_cast<unsigned char*>(data);
+  ByteSource::Builder buf(params.length);
 
   // Both pass and salt may be zero length here.
   // The generated bytes are stored in buf, which is
   // assigned to out on success.
 
-  if (PKCS5_PBKDF2_HMAC(
-          params.pass.get(),
-          params.pass.size(),
-          params.salt.data<unsigned char>(),
-          params.salt.size(),
-          params.iterations,
-          params.digest,
-          params.length,
-          ptr) <= 0) {
+  if (PKCS5_PBKDF2_HMAC(params.pass.data<char>(),
+                        params.pass.size(),
+                        params.salt.data<unsigned char>(),
+                        params.salt.size(),
+                        params.iterations,
+                        params.digest,
+                        params.length,
+                        buf.data<unsigned char>()) <= 0) {
     return false;
   }
-  *out = std::move(buf);
+  *out = std::move(buf).release();
   return true;
 }
 
diff --git a/src/crypto/crypto_random.cc b/src/crypto/crypto_random.cc
index 648fda211c4..d0736a9cf12 100644
--- a/src/crypto/crypto_random.cc
+++ b/src/crypto/crypto_random.cc
@@ -222,9 +222,9 @@ bool CheckPrimeTraits::DeriveBits(
             ctx.get(),
             nullptr);
   if (ret < 0) return false;
-  char* data = MallocOpenSSL<char>(1);
-  data[0] = ret;
-  *out = ByteSource::Allocated(data, 1);
+  ByteSource::Builder buf(1);
+  buf.data<char>()[0] = ret;
+  *out = std::move(buf).release();
   return true;
 }
 
@@ -233,7 +233,7 @@ Maybe<bool> CheckPrimeTraits::EncodeOutput(
     const CheckPrimeConfig& params,
     ByteSource* out,
     v8::Local<v8::Value>* result) {
-  *result = out->get()[0] ? True(env->isolate()) : False(env->isolate());
+  *result = out->data<char>()[0] ? True(env->isolate()) : False(env->isolate());
   return Just(true);
 }
 
diff --git a/src/crypto/crypto_rsa.cc b/src/crypto/crypto_rsa.cc
index bd732a70a8f..57cec1a8fd2 100644
--- a/src/crypto/crypto_rsa.cc
+++ b/src/crypto/crypto_rsa.cc
@@ -223,7 +223,7 @@ WebCryptoCipherStatus RSA_Cipher(
 
   size_t label_len = params.label.size();
   if (label_len > 0) {
-    void* label = OPENSSL_memdup(params.label.get(), label_len);
+    void* label = OPENSSL_memdup(params.label.data<char>(), label_len);
     CHECK_NOT_NULL(label);
     if (EVP_PKEY_CTX_set0_rsa_oaep_label(
       ctx.get(),
@@ -244,22 +244,17 @@ WebCryptoCipherStatus RSA_Cipher(
     return WebCryptoCipherStatus::FAILED;
   }
 
-  char* data = MallocOpenSSL<char>(out_len);
-  ByteSource buf = ByteSource::Allocated(data, out_len);
-  unsigned char* ptr = reinterpret_cast<unsigned char*>(data);
+  ByteSource::Builder buf(out_len);
 
-  if (cipher(
-          ctx.get(),
-          ptr,
-          &out_len,
-          in.data<unsigned char>(),
-          in.size()) <= 0) {
+  if (cipher(ctx.get(),
+             buf.data<unsigned char>(),
+             &out_len,
+             in.data<unsigned char>(),
+             in.size()) <= 0) {
     return WebCryptoCipherStatus::FAILED;
   }
 
-  buf.Resize(out_len);
-
-  *out = std::move(buf);
+  *out = std::move(buf).release(out_len);
   return WebCryptoCipherStatus::OK;
 }
 }  // namespace
diff --git a/src/crypto/crypto_scrypt.cc b/src/crypto/crypto_scrypt.cc
index 4ddf705703c..88d355446c0 100644
--- a/src/crypto/crypto_scrypt.cc
+++ b/src/crypto/crypto_scrypt.cc
@@ -121,26 +121,23 @@ bool ScryptTraits::DeriveBits(
     Environment* env,
     const ScryptConfig& params,
     ByteSource* out) {
-  char* data = MallocOpenSSL<char>(params.length);
-  ByteSource buf = ByteSource::Allocated(data, params.length);
-  unsigned char* ptr = reinterpret_cast<unsigned char*>(data);
+  ByteSource::Builder buf(params.length);
 
   // Both the pass and salt may be zero-length at this point
 
-  if (!EVP_PBE_scrypt(
-          params.pass.get(),
-          params.pass.size(),
-          params.salt.data<unsigned char>(),
-          params.salt.size(),
-          params.N,
-          params.r,
-          params.p,
-          params.maxmem,
-          ptr,
-          params.length)) {
+  if (!EVP_PBE_scrypt(params.pass.data<char>(),
+                      params.pass.size(),
+                      params.salt.data<unsigned char>(),
+                      params.salt.size(),
+                      params.N,
+                      params.r,
+                      params.p,
+                      params.maxmem,
+                      buf.data<unsigned char>(),
+                      params.length)) {
     return false;
   }
-  *out = std::move(buf);
+  *out = std::move(buf).release();
   return true;
 }
 
diff --git a/src/crypto/crypto_sig.cc b/src/crypto/crypto_sig.cc
index c4483a71744..a72649ab8ec 100644
--- a/src/crypto/crypto_sig.cc
+++ b/src/crypto/crypto_sig.cc
@@ -174,18 +174,15 @@ ByteSource ConvertSignatureToP1363(
   if (n == kNoDsaSignature)
     return ByteSource();
 
-  const unsigned char* sig_data =
-      reinterpret_cast<const unsigned char*>(signature.get());
+  const unsigned char* sig_data = signature.data<unsigned char>();
 
-  char* outdata = MallocOpenSSL<char>(n * 2);
-  memset(outdata, 0, n * 2);
-  ByteSource out = ByteSource::Allocated(outdata, n * 2);
-  unsigned char* ptr = reinterpret_cast<unsigned char*>(outdata);
+  ByteSource::Builder out(n * 2);
+  memset(out.data<void>(), 0, n * 2);
 
-  if (!ExtractP1363(sig_data, ptr, signature.size(), n))
+  if (!ExtractP1363(sig_data, out.data<unsigned char>(), signature.size(), n))
     return ByteSource();
 
-  return out;
+  return std::move(out).release();
 }
 
 ByteSource ConvertSignatureToDER(
@@ -195,8 +192,7 @@ ByteSource ConvertSignatureToDER(
   if (n == kNoDsaSignature)
     return std::move(out);
 
-  const unsigned char* sig_data =
-      reinterpret_cast<const unsigned char*>(out.get());
+  const unsigned char* sig_data = out.data<unsigned char>();
 
   if (out.size() != 2 * n)
     return ByteSource();
@@ -526,7 +522,7 @@ SignBase::Error Verify::VerifyFinal(const ManagedEVPPKey& pkey,
       ApplyRSAOptions(pkey, pkctx.get(), padding, saltlen) &&
       EVP_PKEY_CTX_set_signature_md(pkctx.get(),
                                     EVP_MD_CTX_md(mdctx.get())) > 0) {
-    const unsigned char* s = reinterpret_cast<const unsigned char*>(sig.get());
+    const unsigned char* s = sig.data<unsigned char>();
     const int r = EVP_PKEY_verify(pkctx.get(), s, sig.size(), m, m_len);
     *verify_result = r == 1;
   }
@@ -570,7 +566,7 @@ void Verify::VerifyFinal(const FunctionCallbackInfo<Value>& args) {
   ByteSource signature = hbuf.ToByteSource();
   if (dsa_sig_enc == kSigEncP1363) {
     signature = ConvertSignatureToDER(pkey, hbuf.ToByteSource());
-    if (signature.get() == nullptr)
+    if (signature.data() == nullptr)
       return crypto::CheckThrow(env, Error::kSignMalformedSignature);
   }
 
@@ -746,9 +742,8 @@ bool SignTraits::DeriveBits(
 
   switch (params.mode) {
     case SignConfiguration::kSign: {
-      size_t len;
-      unsigned char* data = nullptr;
       if (IsOneShot(params.key)) {
+        size_t len;
         if (!EVP_DigestSign(
             context.get(),
             nullptr,
@@ -758,20 +753,18 @@ bool SignTraits::DeriveBits(
           crypto::CheckThrow(env, SignBase::Error::kSignPrivateKey);
           return false;
         }
-        data = MallocOpenSSL<unsigned char>(len);
-        if (!EVP_DigestSign(
-            context.get(),
-            data,
-            &len,
-            params.data.data<unsigned char>(),
-            params.data.size())) {
-              crypto::CheckThrow(env, SignBase::Error::kSignPrivateKey);
-              return false;
-            }
-        ByteSource buf =
-            ByteSource::Allocated(reinterpret_cast<char*>(data), len);
-        *out = std::move(buf);
+        ByteSource::Builder buf(len);
+        if (!EVP_DigestSign(context.get(),
+                            buf.data<unsigned char>(),
+                            &len,
+                            params.data.data<unsigned char>(),
+                            params.data.size())) {
+          crypto::CheckThrow(env, SignBase::Error::kSignPrivateKey);
+          return false;
+        }
+        *out = std::move(buf).release(len);
       } else {
+        size_t len;
         if (!EVP_DigestSignUpdate(
                 context.get(),
                 params.data.data<unsigned char>(),
@@ -780,35 +773,34 @@ bool SignTraits::DeriveBits(
           crypto::CheckThrow(env, SignBase::Error::kSignPrivateKey);
           return false;
         }
-        data = MallocOpenSSL<unsigned char>(len);
-        ByteSource buf =
-            ByteSource::Allocated(reinterpret_cast<char*>(data), len);
-        if (!EVP_DigestSignFinal(context.get(), data, &len)) {
+        ByteSource::Builder buf(len);
+        if (!EVP_DigestSignFinal(
+                context.get(), buf.data<unsigned char>(), &len)) {
           crypto::CheckThrow(env, SignBase::Error::kSignPrivateKey);
           return false;
         }
 
         if (UseP1363Encoding(params.key, params.dsa_encoding)) {
-          *out = ConvertSignatureToP1363(env, params.key, buf);
+          *out = ConvertSignatureToP1363(
+              env, params.key, std::move(buf).release());
         } else {
-          buf.Resize(len);
-          *out = std::move(buf);
+          *out = std::move(buf).release(len);
         }
       }
       break;
     }
     case SignConfiguration::kVerify: {
-      char* data = MallocOpenSSL<char>(1);
-      data[0] = 0;
-      *out = ByteSource::Allocated(data, 1);
+      ByteSource::Builder buf(1);
+      buf.data<char>()[0] = 0;
       if (EVP_DigestVerify(
               context.get(),
               params.signature.data<unsigned char>(),
               params.signature.size(),
               params.data.data<unsigned char>(),
               params.data.size()) == 1) {
-        data[0] = 1;
+        buf.data<char>()[0] = 1;
       }
+      *out = std::move(buf).release();
     }
   }
 
@@ -825,9 +817,8 @@ Maybe<bool> SignTraits::EncodeOutput(
       *result = out->ToArrayBuffer(env);
       break;
     case SignConfiguration::kVerify:
-      *result = out->get()[0] == 1
-          ? v8::True(env->isolate())
-          : v8::False(env->isolate());
+      *result = out->data<char>()[0] == 1 ? v8::True(env->isolate())
+                                          : v8::False(env->isolate());
       break;
     default:
       UNREACHABLE();
diff --git a/src/crypto/crypto_spkac.cc b/src/crypto/crypto_spkac.cc
index c29d94edc0f..7cda346907e 100644
--- a/src/crypto/crypto_spkac.cc
+++ b/src/crypto/crypto_spkac.cc
@@ -122,7 +122,7 @@ void ExportChallenge(const FunctionCallbackInfo<Value>& args) {
     return args.GetReturnValue().SetEmptyString();
 
   Local<Value> outString =
-      Encode(env->isolate(), cert.get(), cert.size(), BUFFER);
+      Encode(env->isolate(), cert.data<char>(), cert.size(), BUFFER);
 
   args.GetReturnValue().Set(outString);
 }
diff --git a/src/crypto/crypto_util.cc b/src/crypto/crypto_util.cc
index 58a5d88d7a1..5d8f0bbe8e3 100644
--- a/src/crypto/crypto_util.cc
+++ b/src/crypto/crypto_util.cc
@@ -89,7 +89,7 @@ int PasswordCallback(char* buf, int size, int rwflag, void* u) {
     size_t len = passphrase->size();
     if (buflen < len)
       return -1;
-    memcpy(buf, passphrase->get(), len);
+    memcpy(buf, passphrase->data(), len);
     return len;
   }
 
@@ -327,12 +327,6 @@ ByteSource::~ByteSource() {
   OPENSSL_clear_free(allocated_data_, size_);
 }
 
-void ByteSource::reset() {
-  OPENSSL_clear_free(allocated_data_, size_);
-  data_ = nullptr;
-  size_ = 0;
-}
-
 ByteSource& ByteSource::operator=(ByteSource&& other) noexcept {
   if (&other != this) {
     OPENSSL_clear_free(allocated_data_, size_);
@@ -371,45 +365,29 @@ MaybeLocal<Uint8Array> ByteSource::ToBuffer(Environment* env) {
   return Buffer::New(env, ab, 0, ab->ByteLength());
 }
 
-const char* ByteSource::get() const {
-  return data_;
-}
-
-size_t ByteSource::size() const {
-  return size_;
-}
-
 ByteSource ByteSource::FromBIO(const BIOPointer& bio) {
   CHECK(bio);
   BUF_MEM* bptr;
   BIO_get_mem_ptr(bio.get(), &bptr);
-  char* data = MallocOpenSSL<char>(bptr->length);
-  memcpy(data, bptr->data, bptr->length);
-  return Allocated(data, bptr->length);
+  ByteSource::Builder out(bptr->length);
+  memcpy(out.data<void>(), bptr->data, bptr->length);
+  return std::move(out).release();
 }
 
 ByteSource ByteSource::FromEncodedString(Environment* env,
                                          Local<String> key,
                                          enum encoding enc) {
   size_t length = 0;
-  size_t actual = 0;
-  char* data = nullptr;
+  ByteSource out;
 
   if (StringBytes::Size(env->isolate(), key, enc).To(&length) && length > 0) {
-    data = MallocOpenSSL<char>(length);
-    actual = StringBytes::Write(env->isolate(), data, length, key, enc);
-
-    CHECK(actual <= length);
-
-    if (actual == 0) {
-      OPENSSL_clear_free(data, length);
-      data = nullptr;
-    } else if (actual < length) {
-      data = reinterpret_cast<char*>(OPENSSL_realloc(data, actual));
-    }
+    ByteSource::Builder buf(length);
+    size_t actual =
+        StringBytes::Write(env->isolate(), buf.data<char>(), length, key, enc);
+    out = std::move(buf).release(actual);
   }
 
-  return Allocated(data, actual);
+  return out;
 }
 
 ByteSource ByteSource::FromStringOrBuffer(Environment* env,
@@ -423,11 +401,11 @@ ByteSource ByteSource::FromString(Environment* env, Local<String> str,
   CHECK(str->IsString());
   size_t size = str->Utf8Length(env->isolate());
   size_t alloc_size = ntc ? size + 1 : size;
-  char* data = MallocOpenSSL<char>(alloc_size);
+  ByteSource::Builder out(alloc_size);
   int opts = String::NO_OPTIONS;
   if (!ntc) opts |= String::NO_NULL_TERMINATION;
-  str->WriteUtf8(env->isolate(), data, alloc_size, nullptr, opts);
-  return Allocated(data, size);
+  str->WriteUtf8(env->isolate(), out.data<char>(), alloc_size, nullptr, opts);
+  return std::move(out).release();
 }
 
 ByteSource ByteSource::FromBuffer(Local<Value> buffer, bool ntc) {
@@ -460,16 +438,11 @@ ByteSource ByteSource::FromSymmetricKeyObjectHandle(Local<Value> handle) {
                  key->Data()->GetSymmetricKeySize());
 }
 
-ByteSource::ByteSource(const char* data, char* allocated_data, size_t size)
-    : data_(data),
-      allocated_data_(allocated_data),
-      size_(size) {}
-
-ByteSource ByteSource::Allocated(char* data, size_t size) {
+ByteSource ByteSource::Allocated(void* data, size_t size) {
   return ByteSource(data, data, size);
 }
 
-ByteSource ByteSource::Foreign(const char* data, size_t size) {
+ByteSource ByteSource::Foreign(const void* data, size_t size) {
   return ByteSource(data, nullptr, size);
 }
 
diff --git a/src/crypto/crypto_util.h b/src/crypto/crypto_util.h
index 7a795fe5e81..e5d9410039c 100644
--- a/src/crypto/crypto_util.h
+++ b/src/crypto/crypto_util.h
@@ -29,11 +29,12 @@
 #endif  // OPENSSL_FIPS
 
 #include <algorithm>
+#include <climits>
+#include <cstdio>
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
-#include <climits>
-#include <cstdio>
 
 namespace node {
 namespace crypto {
@@ -218,37 +219,74 @@ T* MallocOpenSSL(size_t count) {
   return static_cast<T*>(mem);
 }
 
-template <typename T>
-T* ReallocOpenSSL(T* buf, size_t count) {
-  void* mem = OPENSSL_realloc(buf, MultiplyWithOverflowCheck(count, sizeof(T)));
-  CHECK_IMPLIES(mem == nullptr, count == 0);
-  return static_cast<T*>(mem);
-}
-
 // A helper class representing a read-only byte array. When deallocated, its
 // contents are zeroed.
 class ByteSource {
  public:
+  class Builder {
+   public:
+    // Allocates memory using OpenSSL's memory allocator.
+    explicit Builder(size_t size)
+        : data_(MallocOpenSSL<char>(size)), size_(size) {}
+
+    Builder(Builder&& other) = delete;
+    Builder& operator=(Builder&& other) = delete;
+    Builder(const Builder&) = delete;
+    Builder& operator=(const Builder&) = delete;
+
+    ~Builder() { OPENSSL_clear_free(data_, size_); }
+
+    // Returns the underlying non-const pointer.
+    template <typename T>
+    T* data() {
+      return reinterpret_cast<T*>(data_);
+    }
+
+    // Returns the (allocated) size in bytes.
+    size_t size() const { return size_; }
+
+    // Finalizes the Builder and returns a read-only view that is optionally
+    // truncated.
+    ByteSource release(std::optional<size_t> resize = std::nullopt) && {
+      if (resize) {
+        CHECK_LE(*resize, size_);
+        if (*resize == 0) {
+          OPENSSL_clear_free(data_, size_);
+          data_ = nullptr;
+        }
+        size_ = *resize;
+      }
+      ByteSource out = ByteSource::Allocated(data_, size_);
+      data_ = nullptr;
+      size_ = 0;
+      return out;
+    }
+
+   private:
+    void* data_;
+    size_t size_;
+  };
+
   ByteSource() = default;
   ByteSource(ByteSource&& other) noexcept;
   ~ByteSource();
 
   ByteSource& operator=(ByteSource&& other) noexcept;
 
-  const char* get() const;
+  ByteSource(const ByteSource&) = delete;
+  ByteSource& operator=(const ByteSource&) = delete;
 
-  template <typename T>
-  const T* data() const { return reinterpret_cast<const T*>(get()); }
+  template <typename T = void>
+  const T* data() const {
+    return reinterpret_cast<const T*>(data_);
+  }
 
-  size_t size() const;
+  size_t size() const { return size_; }
 
   operator bool() const { return data_ != nullptr; }
 
   BignumPointer ToBN() const {
-    return BignumPointer(BN_bin2bn(
-        reinterpret_cast<const unsigned char*>(get()),
-        size(),
-        nullptr));
+    return BignumPointer(BN_bin2bn(data<unsigned char>(), size(), nullptr));
   }
 
   // Creates a v8::BackingStore that takes over responsibility for
@@ -260,19 +298,8 @@ class ByteSource {
 
   v8::MaybeLocal<v8::Uint8Array> ToBuffer(Environment* env);
 
-  void reset();
-
-  // Allows an Allocated ByteSource to be truncated.
-  void Resize(size_t newsize) {
-    CHECK_LE(newsize, size_);
-    CHECK_NOT_NULL(allocated_data_);
-    char* new_data_ = ReallocOpenSSL<char>(allocated_data_, newsize);
-    data_ = allocated_data_ = new_data_;
-    size_ = newsize;
-  }
-
-  static ByteSource Allocated(char* data, size_t size);
-  static ByteSource Foreign(const char* data, size_t size);
+  static ByteSource Allocated(void* data, size_t size);
+  static ByteSource Foreign(const void* data, size_t size);
 
   static ByteSource FromEncodedString(Environment* env,
                                       v8::Local<v8::String> value,
@@ -295,18 +322,16 @@ class ByteSource {
 
   static ByteSource FromSymmetricKeyObjectHandle(v8::Local<v8::Value> handle);
 
-  ByteSource(const ByteSource&) = delete;
-  ByteSource& operator=(const ByteSource&) = delete;
-
   static ByteSource FromSecretKeyBytes(
       Environment* env, v8::Local<v8::Value> value);
 
  private:
-  const char* data_ = nullptr;
-  char* allocated_data_ = nullptr;
+  const void* data_ = nullptr;
+  void* allocated_data_ = nullptr;
   size_t size_ = 0;
 
-  ByteSource(const char* data, char* allocated_data, size_t size);
+  ByteSource(const void* data, void* allocated_data, size_t size)
+      : data_(data), allocated_data_(allocated_data), size_(size) {}
 };
 
 enum CryptoJobMode {