fix(ext/node): resource leak in createHmac (#18229)

This commit fixes https://github.com/denoland/deno/issues/18140.
Verified that test fails on `main`.

2 files changed, 26 insertions, 2 deletions

diff --git a/cli/tests/unit_node/crypto_hash.ts b/cli/tests/unit_node/crypto_hash.ts
new file mode 100644
index 000000000..fae66e024
--- /dev/null
+++ b/cli/tests/unit_node/crypto_hash.ts
@@ -0,0 +1,24 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+import { createHash, createHmac } from "node:crypto";
+import { assertEquals } from "../../../test_util/std/testing/asserts.ts";
+
+// https://github.com/denoland/deno/issues/18140
+Deno.test({
+  name: "createHmac digest",
+  fn() {
+    assertEquals(
+      createHmac("sha256", "secret").update("hello").digest("hex"),
+      "88aab3ede8d3adf94d26ab90d3bafd4a2083070c3bcce9c014ee04a443847c0b",
+    );
+  },
+});
+
+Deno.test({
+  name: "createHash digest",
+  fn() {
+    assertEquals(
+      createHash("sha256").update("hello").digest("hex"),
+      "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824",
+    );
+  },
+});
diff --git a/ext/node/polyfills/internal/crypto/hash.ts b/ext/node/polyfills/internal/crypto/hash.ts
index de7b16297..d81844f30 100644
--- a/ext/node/polyfills/internal/crypto/hash.ts
+++ b/ext/node/polyfills/internal/crypto/hash.ts
@@ -178,7 +178,6 @@ class HmacImpl extends Transform {
     const u8Key = prepareSecretKey(key, options?.encoding) as Buffer;
 
     const alg = hmac.toLowerCase();
-    this.#hash = new Hash(alg, options);
     this.#algorithm = alg;
     const blockSize = (alg === "sha512" || alg === "sha384") ? 128 : 64;
     const keySize = u8Key.length;
@@ -186,7 +185,8 @@ class HmacImpl extends Transform {
     let bufKey: Buffer;
 
     if (keySize > blockSize) {
-      bufKey = this.#hash.update(u8Key).digest() as Buffer;
+      const hash = new Hash(alg, options);
+      bufKey = hash.update(u8Key).digest() as Buffer;
     } else {
       bufKey = Buffer.concat([u8Key, this.#ZEROES], blockSize);
     }