fix(crypto): validate that digest length must be an integer between 0 and isize::MAX

crypto/crypto.ts

@@ -220,6 +220,9 @@ const stdCrypto: StdCrypto = ((x) => x)({
       data: BufferSource | AsyncIterable<BufferSource> | Iterable<BufferSource>,
     ): Promise<ArrayBuffer> {
       const { name, length } = normalizeAlgorithm(algorithm);
+
+      assertValidDigestLength(length);
+
       const bytes = bufferSourceBytes(data);
 
       if (FNVAlgorithms.includes(name)) {
@@ -280,28 +283,30 @@ const stdCrypto: StdCrypto = ((x) => x)({
       algorithm: DigestAlgorithm,
       data: BufferSource | Iterable<BufferSource>,
     ): ArrayBuffer {
-      algorithm = normalizeAlgorithm(algorithm);
+      const { name, length } = normalizeAlgorithm(algorithm);
+
+      assertValidDigestLength(length);
 
       const bytes = bufferSourceBytes(data);
 
-      if (FNVAlgorithms.includes(algorithm.name)) {
-        return fnv(algorithm.name, bytes);
+      if (FNVAlgorithms.includes(name)) {
+        return fnv(name, bytes);
       }
 
       const wasmCrypto = instantiateWasm();
       if (bytes) {
-        return wasmCrypto.digest(algorithm.name, bytes, algorithm.length)
+        return wasmCrypto.digest(name, bytes, length)
           .buffer;
       } else if ((data as Iterable<BufferSource>)[Symbol.iterator]) {
-        const context = new wasmCrypto.DigestContext(algorithm.name);
+        const context = new wasmCrypto.DigestContext(name);
         for (const chunk of data as Iterable<BufferSource>) {
           const chunkBytes = bufferSourceBytes(chunk);
           if (!chunkBytes) {
             throw new TypeError("data contained chunk of the wrong type");
           }
           context.update(chunkBytes);
         }
-        return context.digestAndDrop(algorithm.length).buffer;
+        return context.digestAndDrop(length).buffer;
       } else {
         throw new TypeError(
           "data must be a BufferSource or Iterable<BufferSource>",
@@ -328,6 +333,29 @@ const webCryptoDigestAlgorithms = [
 export type FNVAlgorithms = "FNV32" | "FNV32A" | "FNV64" | "FNV64A";
 export type DigestAlgorithmName = WasmDigestAlgorithm | FNVAlgorithms;
 
+/*
+ * The largest digest length the current WASM implementation can support. This
+ * is the value of `isize::MAX` on 32-bit platforms like WASM, which is the
+ * maximum allowed capacity of a Rust `Vec<u8>`.
+ */
+const MAX_DIGEST_LENGTH = 0x7FFF_FFFF;
+
+/**
+ * Asserts that a number is a valid length for a digest, which must be an
+ * integer that fits in a Rust `Vec<u8>`, or be undefined.
+ */
+function assertValidDigestLength(value?: number) {
+  if (
+    value !== undefined &&
+    (value < 0 || value > MAX_DIGEST_LENGTH ||
+      !Number.isInteger(value))
+  ) {
+    throw new RangeError(
+      `length must be an integer between 0 and ${MAX_DIGEST_LENGTH}, inclusive`,
+    );
+  }
+}
+
 export type DigestAlgorithmObject = {
   name: DigestAlgorithmName;
   length?: number;

crypto/crypto_test.ts

@@ -1,5 +1,5 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
-import { assert, assertEquals, assertInstanceOf } from "../assert/mod.ts";
+import { assert, assertEquals, assertInstanceOf, fail } from "../assert/mod.ts";
 import { crypto as stdCrypto } from "./mod.ts";
 import { repeat } from "../bytes/repeat.ts";
 import { dirname, fromFileUrl } from "../path/mod.ts";
@@ -1363,7 +1363,11 @@ for (const algorithm of digestAlgorithms) {
         const bytePieces = pieces.map((piece) =>
           typeof piece === "string" ? new TextEncoder().encode(piece) : piece
         ) as Array<BufferSource>;
-        try {
+
+        // Expected value will either be a hex string, if the case is expected
+        // to return successfully, or an error class/constructor function, if
+        // the case is expected to throw.
+        if (typeof expected === "string") {
           const actual = toHexString(
             await stdCrypto.subtle.digest({
               ...options,
@@ -1379,15 +1383,32 @@ for (const algorithm of digestAlgorithms) {
               JSON.stringify(options)
             }) returned unexpected value\n  actual: ${actual}\nexpected: ${expected}`,
           );
-        } catch (error) {
-          if (expected instanceof Function) {
-            assert(
-              error instanceof expected,
-              `got a different error than expected: ${error}`,
+        } else if (typeof expected === "function") {
+          let error;
+          try {
+            await stdCrypto.subtle.digest({
+              ...options,
+              name: algorithm,
+            }, bytePieces);
+          } catch (caughtError) {
+            error = caughtError;
+          }
+          if (error !== undefined) {
+            assertInstanceOf(
+              error,
+              expected,
             );
           } else {
-            throw error;
+            fail(
+              `${algorithm} of ${caption}${
+                i > 0 ? ` (but not until variation [${i}]!)` : ""
+              } with options ${
+                JSON.stringify(options)
+              }) expected an exception of type ${expected.name}, but none was thrown.`,
+            );
           }
+        } else {
+          throw new TypeError("expected value has an unexpected type");
         }
       }
     }