buffer: throw on failed fill attempts

If fill() attempts to write a string to a buffer, but fails
silently, then uninitialized memory could be leaked. This commit
causes fill() to throw if the string write operation fails.

Refs: https://github.com/nodejs/node/issues/17423
PR-URL: https://github.com/nodejs/node/pull/17427
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/buffer.js b/lib/buffer.js
index 8899d260ad..40aaf37e09 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -892,8 +892,12 @@ function fill_(buf, val, start, end, encoding) {
 
   start = start >>> 0;
   end = end === undefined ? buf.length : end >>> 0;
+  const fillLength = bindingFill(buf, val, start, end, encoding);
 
-  return bindingFill(buf, val, start, end, encoding);
+  if (fillLength === -1)
+    throw new errors.TypeError('ERR_INVALID_ARG_VALUE', 'value', val);
+
+  return fillLength;
 }