buffer: truncate instead of throw when writing beyond buffer

Fixes: #54523 Fixes: #54518 PR-URL: #54524 Reviewed-By: Ethan Arrowood <ethan@arrowood.dev> Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
nodejs · Aug 30, 2024 · ac178b0 · ac178b0
1 parent e6e1f4e
commit ac178b0
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Showing 2 changed files with 18 additions and 3 deletions.
diff --git a/lib/internal/buffer.js b/lib/internal/buffer.js
@@ -1040,7 +1040,7 @@ function addBufferPrototypeMethods(proto) {
     if (offset < 0 || offset > this.byteLength) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('offset');
     }
-    if (length < 0 || length > this.byteLength - offset) {
+    if (length < 0) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('length');
     }
     return asciiWriteStatic(this, string, offset, length);
@@ -1051,7 +1051,7 @@ function addBufferPrototypeMethods(proto) {
     if (offset < 0 || offset > this.byteLength) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('offset');
     }
-    if (length < 0 || length > this.byteLength - offset) {
+    if (length < 0) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('length');
     }
     return latin1WriteStatic(this, string, offset, length);
@@ -1062,7 +1062,7 @@ function addBufferPrototypeMethods(proto) {
     if (offset < 0 || offset > this.byteLength) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('offset');
     }
-    if (length < 0 || length > this.byteLength - offset) {
+    if (length < 0) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('length');
     }
     return utf8WriteStatic(this, string, offset, length);

diff --git a/test/parallel/test-buffer-write.js b/test/parallel/test-buffer-write.js
@@ -106,3 +106,18 @@ assert.strictEqual(Buffer.alloc(4)
   assert.strictEqual(buf.write('ыы', 1, 'utf16le'), 4);
   assert.deepStrictEqual([...buf], [0, 0x4b, 0x04, 0x4b, 0x04, 0, 0, 0]);
 }
+
+{
+  const buf = Buffer.alloc(1);
+  assert.strictEqual(buf.write('ww'), 1);
+  assert.strictEqual(buf.toString(), 'w');
+}
+
+assert.throws(() => {
+  const buf = Buffer.alloc(1);
+  assert.strictEqual(buf.asciiWrite('ww', 0, -1));
+  assert.strictEqual(buf.latin1Write('ww', 0, -1));
+  assert.strictEqual(buf.utf8Write('ww', 0, -1));
+}, common.expectsError({
+  code: 'ERR_BUFFER_OUT_OF_BOUNDS',
+}));