crypto: fixup randomFill size and offset handling

Signed-off-by: James M Snell <jasnell@gmail.com>

PR-URL: #38138
Fixes: #38137
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/internal/crypto/random.js

@@ -155,10 +155,11 @@ function randomFill(buf, offset, size, callback) {
   if (typeof offset === 'function') {
     callback = offset;
     offset = 0;
-    size = buf.bytesLength;
+    // Size is a length here, assertSize() call turns it into a number of bytes
+    size = buf.length;
   } else if (typeof size === 'function') {
     callback = size;
-    size = buf.byteLength - offset;
+    size = buf.length - offset;
   } else {
     validateCallback(callback);
   }
@@ -176,7 +177,6 @@ function randomFill(buf, offset, size, callback) {
     return;
   }
 
-  // TODO(@jasnell): This is not yet handling byte offsets right
   const job = new RandomBytesJob(
     kCryptoJobAsync,
     buf,

test/parallel/test-crypto-random.js

@@ -525,3 +525,10 @@ assert.throws(
     assert.throws(() => crypto.randomInt(0, 1, i), cbError);
   });
 }
+
+{
+  // Verify that it doesn't throw or abort
+  crypto.randomFill(new Uint16Array(10), 0, common.mustSucceed());
+  crypto.randomFill(new Uint32Array(10), 0, common.mustSucceed());
+  crypto.randomFill(new Uint32Array(10), 0, 1, common.mustSucceed());
+}