nodejs
diff --git a/Collapse file
‎lib/buffer.js‎
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+8Lines changed: 8 additions & 0 deletions b/Collapse file
‎lib/buffer.js‎
Copy file name to clipboardExpand all lines: lib/buffer.js
+8Lines changed: 8 additions & 0 deletions
diff --git a/Collapse file
‎test/parallel/test-buffer-concat.js‎
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+23-1Lines changed: 23 additions & 1 deletion b/Collapse file
‎test/parallel/test-buffer-concat.js‎
Copy file name to clipboardExpand all lines: test/parallel/test-buffer-concat.js
+23-1Lines changed: 23 additions & 1 deletion
@@ -311,6 +311,14 @@ Buffer.concat = function(list, length) {
     pos += buf.length;
   }
 
+  // Note: `length` is always equal to `buffer.length` at this point
+  if (pos < length) {
+    // Zero-fill the remaining bytes if the specified `length` was more than
+    // the actual total length, i.e. if we have some remaining allocated bytes
+    // there were not initialized.
+    buffer.fill(0, pos, length);
+  }
+
   return buffer;
 };
 
 
@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 
 const zero = [];
@@ -38,3 +38,25 @@ function assertWrongList(value) {
            err.message === '"list" argument must be an Array of Buffers';
   });
 }
+
+const random10 = common.hasCrypto
+    ? require('crypto').randomBytes(10)
+    : Buffer.alloc(10, 1);
+const empty = Buffer.alloc(0);
+
+assert.notDeepStrictEqual(random10, empty);
+assert.notDeepStrictEqual(random10, Buffer.alloc(10));
+
+assert.deepStrictEqual(Buffer.concat([], 100), empty);
+assert.deepStrictEqual(Buffer.concat([random10], 0), empty);
+assert.deepStrictEqual(Buffer.concat([random10], 10), random10);
+assert.deepStrictEqual(Buffer.concat([random10, random10], 10), random10);
+assert.deepStrictEqual(Buffer.concat([empty, random10]), random10);
+assert.deepStrictEqual(Buffer.concat([random10, empty, empty]), random10);
+
+// The tail should be zero-filled
+assert.deepStrictEqual(Buffer.concat([empty], 100), Buffer.alloc(100));
+assert.deepStrictEqual(Buffer.concat([empty], 4096), Buffer.alloc(4096));
+assert.deepStrictEqual(
+    Buffer.concat([random10], 40),
+    Buffer.concat([random10, Buffer.alloc(30)]));