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buffer: convert offset & length to int properly · nodejs/node@f83d035 · GitHub

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Commit f83d035

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thefourtheye
authored and
MylesBorins
committed
buffer: convert offset & length to int properly
 As per ecma-262 2015's #sec-%typedarray%-buffer-byteoffset-length, `offset` would be an integer, not a 32 bit unsigned integer. Also, `length` would be an integer with the maximum value of 2^53 - 1, not a 32 bit unsigned integer. This would be a problem because, if we create a buffer from an arraybuffer, from an offset which is greater than 2^32, it would be actually pointing to a different location in arraybuffer. For example, if we use 2^40 as offset, then the actual value used will be 0, because `byteOffset >>>= 0` will convert `byteOffset` to a 32 bit unsigned int, which is based on 2^32 modulo. This is a redo, as the ca37fa5 broke CI. Refer: #9814 Refer: #9492 PR-URL: #9815 Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Backport-Of: #9815 PR-URL: #11176 Reviewed-By: James M Snell <jasnell@gmail.com>
1 parent 87760cc commit f83d035

5 files changed

Lines changed: 128 additions & 2 deletions

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‎lib/buffer.js‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -216,7 +216,7 @@ function fromArrayLike(obj) {
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}
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218218
function fromArrayBuffer(obj, byteOffset, length) {
219-
byteOffset >>>= 0;
219+
byteOffset = internalUtil.toInteger(byteOffset);
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221221
const maxLength = obj.byteLength - byteOffset;
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@@ -226,7 +226,7 @@ function fromArrayBuffer(obj, byteOffset, length) {
226226
if (length === undefined) {
227227
length = maxLength;
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} else {
229-
length >>>= 0;
229+
length = internalUtil.toLength(length);
230230
if (length > maxLength)
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throw new RangeError("'length' is out of bounds");
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}

‎lib/internal/util.js‎

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -165,3 +165,21 @@ exports.normalizeEncoding = function normalizeEncoding(enc) {
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}
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}
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};
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/*
170+
* Implementation of ToInteger as per ECMAScript Specification
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* Refer: http://www.ecma-international.org/ecma-262/6.0/#sec-tointeger
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*/
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const toInteger = exports.toInteger = function toInteger(argument) {
174+
const number = +argument;
175+
return Number.isNaN(number) ? 0 : Math.trunc(number);
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};
177+
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/*
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* Implementation of ToLength as per ECMAScript Specification
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* Refer: http://www.ecma-international.org/ecma-262/6.0/#sec-tolength
181+
*/
182+
exports.toLength = function toLength(argument) {
183+
const len = toInteger(argument);
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return len <= 0 ? 0 : Math.min(len, Number.MAX_SAFE_INTEGER);
185+
};

‎test/parallel/test-buffer-creation-regression.js‎

Lines changed: 41 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,41 @@
1+
'use strict';
2+
3+
const common = require('../common');
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const assert = require('assert');
5+
6+
function test(arrayBuffer, offset, length) {
7+
const uint8Array = new Uint8Array(arrayBuffer, offset, length);
8+
for (let i = 0; i < length; i += 1) {
9+
uint8Array[i] = 1;
10+
}
11+
12+
const buffer = Buffer.from(arrayBuffer, offset, length);
13+
for (let i = 0; i < length; i += 1) {
14+
assert.strictEqual(buffer[i], 1);
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}
16+
}
17+
18+
const acceptableOOMErrors = [
19+
'Array buffer allocation failed',
20+
'Invalid array buffer length'
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];
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const testCases = [
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[200, 50, 100],
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[4294967296 /* 1 << 32 */, 2147483648 /* 1 << 31 */, 1000],
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[8589934592 /* 1 << 33 */, 4294967296 /* 1 << 32 */, 1000]
27+
];
28+
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for (let index = 0, arrayBuffer; index < testCases.length; index += 1) {
30+
const [size, offset, length] = testCases[index];
31+
32+
try {
33+
arrayBuffer = new ArrayBuffer(size);
34+
} catch (e) {
35+
if (e instanceof RangeError && acceptableOOMErrors.includes(e.message))
36+
return common.skip(`Unable to allocate ${size} bytes for ArrayBuffer`);
37+
throw e;
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}
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test(arrayBuffer, offset, length);
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}

‎test/parallel/test-internal-util-toInteger.js‎

Lines changed: 32 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,32 @@
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// Flags: --expose-internals
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'use strict';
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require('../common');
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const assert = require('assert');
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const {toInteger} = require('internal/util');
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const expectZero = [
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'0', '-0', NaN, {}, [], {'a': 'b'}, [1, 2], '0x', '0o', '0b', false,
10+
'', ' ', undefined, null
11+
];
12+
expectZero.forEach(function(value) {
13+
assert.strictEqual(toInteger(value), 0);
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});
15+
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assert.strictEqual(toInteger(Infinity), Infinity);
17+
assert.strictEqual(toInteger(-Infinity), -Infinity);
18+
19+
const expectSame = [
20+
'0x100', '0o100', '0b100', 0x100, -0x100, 0o100, -0o100, 0b100, -0b100, true
21+
];
22+
expectSame.forEach(function(value) {
23+
assert.strictEqual(toInteger(value), +value, `${value} is not an Integer`);
24+
});
25+
26+
const expectIntegers = new Map([
27+
[[1], 1], [[-1], -1], [['1'], 1], [['-1'], -1],
28+
[3.14, 3], [-3.14, -3], ['3.14', 3], ['-3.14', -3],
29+
]);
30+
expectIntegers.forEach(function(expected, value) {
31+
assert.strictEqual(toInteger(value), expected);
32+
});

‎test/parallel/test-internal-util-toLength.js‎

Lines changed: 35 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,35 @@
1+
// Flags: --expose-internals
2+
'use strict';
3+
4+
require('../common');
5+
const assert = require('assert');
6+
const {toLength} = require('internal/util');
7+
const maxValue = Number.MAX_SAFE_INTEGER;
8+
9+
const expectZero = [
10+
'0', '-0', NaN, {}, [], {'a': 'b'}, [1, 2], '0x', '0o', '0b', false,
11+
'', ' ', undefined, null, -1, -1.25, -1.1, -1.9, -Infinity
12+
];
13+
expectZero.forEach(function(value) {
14+
assert.strictEqual(toLength(value), 0);
15+
});
16+
17+
assert.strictEqual(toLength(maxValue - 1), maxValue - 1);
18+
assert.strictEqual(maxValue, maxValue);
19+
assert.strictEqual(toLength(Infinity), maxValue);
20+
assert.strictEqual(toLength(maxValue + 1), maxValue);
21+
22+
23+
[
24+
'0x100', '0o100', '0b100', 0x100, -0x100, 0o100, -0o100, 0b100, -0b100, true
25+
].forEach(function(value) {
26+
assert.strictEqual(toLength(value), +value > 0 ? +value : 0);
27+
});
28+
29+
const expectIntegers = new Map([
30+
[[1], 1], [[-1], 0], [['1'], 1], [['-1'], 0],
31+
[3.14, 3], [-3.14, 0], ['3.14', 3], ['-3.14', 0],
32+
]);
33+
expectIntegers.forEach(function(expected, value) {
34+
assert.strictEqual(toLength(value), expected);
35+
});

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