where does non-zero data in Buffer.allocUnsafeSlow come from?

[LongTengDao]

Details

1. [ ] from any os memory on the machine
2. [ ] only from the process itself gc

If 1, I think need to use --zero-fill-buffers for sandbox process; if 2, without unnecessary use of --zero-fill-buffers, there will be better performance.

So which is it? And I'm I right that if 1, --zero-fill-buffers is unnecessary for security? Or it will still leak some information I can't imagine?

Node.js version

Any, at least for the future.

Example code

No response

Operating system

any

Scope

runtime

Module and version

No response

[gireeshpunathil]

the memory that the buffer allocator gets can be both:

• memory pages from the OS, previously not used by the process
• memory pages (still from the OS), previously used by the process

it does not matter whether you (the process) get your own pages or external pages. what matters is whether it has stale data .

if all the processes make sure to erase sensitive data before they free their memory, the problem do not arise. if not, irrespective of where the memory comes from (your own process versus other process), it can bring an undesired scenario.

in this context, the sensitive data is not a process-scopped entity. by zero-filling the allocations, we are making sure that we are using a clean page and following a best practice in this area.

hope this helps!

[LongTengDao]

Thank you!