buffer: recreate pooled ArrayBuffer after transfer

[lindsaycode05]

Fixes #61362

Summary

• After a Buffer backed by the internal pool has its ArrayBuffer detached (e.g. via ArrayBuffer.prototype.transfer()), subsequent Buffer.from(..., 'base64') calls would throw ERR_BUFFER_OUT_OF_BOUNDS. This change ensures pooled Buffer creation doesn’t rely on a detached pool ArrayBuffer.

Repro

const base64 = Buffer.from('hello', 'utf8').toString('base64');
const first = Buffer.from(base64, 'base64');
first.buffer.transfer();
Buffer.from(base64, 'base64'); // threw `ERR_BUFFER_OUT_OF_BOUNDS` before, succeeds now

Changes

• Add a pool-detachment guard before pooled allocations.
• Add a regression test for pooled base64 Buffer.from after transfer.

Tests

• python3 tools/test.py test/parallel/test-buffer-pool-untransferable.js
• make -j4 test

[legendecas]

The buffer should not be transferrable at all... This still transfers the underlying buffer.

[ChALkeR]

This just masks the issue.

const base64 = Buffer.from('hello', 'utf8').toString('base64');
const first = Buffer.from(base64, 'base64');
first.buffer.transfer();

this could have corrupted other buffers allocated prior to first, not just the ones allocated after that

> x = Buffer.from('hello')
<Buffer 68 65 6c 6c 6f>
> y = Buffer.from('world')
<Buffer 77 6f 72 6c 64>
> y.buffer.transfer()

> x
<Buffer >
> 

Which could also include buffers allocated by Node.js internally
Destroying operations on pooled Buffer .buffer are the problem here, not just the future buffer allocs

[Renegade334]

Thanks for the PR!

Ultimately, I think #61372 is the correct approach here. As Nikita mentioned, this doesn't really solve the underlying issue.

[lindsaycode05]

Thanks guys, that makes sense. Given the broader semantics (detaching a shared backing store invalidates all views), my PR isn’t the right, long-term fix. I’ll leave it to #61372 and maintainer direction from here. Appreciate the discussion and pointers! Feel free to close this PR whenever convenient.