First typed array is not zero-filled (v5.10.0)

[mbloch]

Version: v5.10.0
Platform: Darwin [...] 14.5.0 Darwin Kernel Version 14.5.0: Mon Jan 11 18:48:35 PST 2016; root:xnu-2782.50.2~1/RELEASE_X86_64 x86_64

The first typed array created during script execution may contain non-zero values. Subsequent typed arrays are zero-filled, as expected.

I began to see this behavior after installing v5.10.0 from the following source: https://nodejs.org/dist/v5.10.0/node-v5.10.0-darwin-x64.tar.gz

The previous version, 5.9.1, is not affected.

I'm pasting sample output from the attached script zerofill_bug.txt below.

zerofill_bug.txt

File contents

#!/usr/bin/env node
console.log(new Float64Array(10));
console.log(new Float64Array(10));

Sample output

Float64Array {
  '0': 0,
  '1': 0,
  '2': 2.146862934e-314,
  '3': 2.1468647947e-314,
  '4': 2.146864866e-314,
  '5': 2.1468649963e-314,
  '6': 2.146865024e-314,
  '7': 5.56270611491583e-309,
  '8': 2.3194251029888626e+242,
  '9': 9.765157996892863e+199 }
Float64Array {
  '0': 0,
  '1': 0,
  '2': 0,
  '3': 0,
  '4': 0,
  '5': 0,
  '6': 0,
  '7': 0,
  '8': 0,
  '9': 0 }

[MylesBorins]

I am able to reproduce. Not sure if the labels I have applied are correct or not. I'm doing a bisect right now to see what's up

/cc @nodejs/security

[evanlucas]

Hm, I cannot reproduce it from the repl though...weird

[vkurchatkin]

@evanlucas probably because some allocations are already made

[MylesBorins]

Looks like the regression comes in from 3c02727

edit: wrong sha at first

[evanlucas]

master is affected also

[MylesBorins]

/cc @jasnell

[MylesBorins]

I'm not 100% but I'm going to guess we are doing something wrong here 3c02727#diff-cd53544f44aab2c697bcd7b6a57f23ccR949

[vkurchatkin]

Calling Buffer.allocUnsafe reproduces this state

[evanlucas]

Passing the --zero-fill-buffers flag definitely makes it work

[jasnell]

@thealphanerd ... quick test on v5.x with that additional check removed still shows the problem. Master includes that exact same check also and I'm unable to reproduce there.