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stream: fix highWaterMark integer overflow
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Fixes integer overflows when supplying values exceeding MAX_SAFE_INTEGER
for highWaterMark.

PR-URL: #12593
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Luca Maraschi <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
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tniessen authored and mcollina committed May 16, 2017
1 parent 7906ed5 commit 11918c4
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Showing 3 changed files with 20 additions and 2 deletions.
2 changes: 1 addition & 1 deletion lib/_stream_readable.js
Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,7 @@ function ReadableState(options, stream) {
this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm;

// cast to ints.
this.highWaterMark = ~~this.highWaterMark;
this.highWaterMark = Math.floor(this.highWaterMark);

// A linked list is used to store data chunks instead of an array because the
// linked list can remove elements from the beginning faster than
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2 changes: 1 addition & 1 deletion lib/_stream_writable.js
Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@ function WritableState(options, stream) {
this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm;

// cast to ints.
this.highWaterMark = ~~this.highWaterMark;
this.highWaterMark = Math.floor(this.highWaterMark);

// drain event flag.
this.needDrain = false;
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18 changes: 18 additions & 0 deletions test/parallel/test-streams-highwatermark.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
'use strict';
require('../common');

// This test ensures that the stream implementation correctly handles values
// for highWaterMark which exceed the range of signed 32 bit integers.

const assert = require('assert');
const stream = require('stream');

// This number exceeds the range of 32 bit integer arithmetic but should still
// be handled correctly.
const ovfl = Number.MAX_SAFE_INTEGER;

const readable = stream.Readable({ highWaterMark: ovfl });
assert.strictEqual(readable._readableState.highWaterMark, ovfl);

const writable = stream.Writable({ highWaterMark: ovfl });
assert.strictEqual(writable._writableState.highWaterMark, ovfl);

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