Changing Buffer.length, possible to read/write to neighboring Buffers

[hakovala]

Length of the Buffer can be changed after creating the Buffer even though Buffer has fixed size. Writing outside of the buffers initial size will override content in other neighboring Buffers.

Here's a simple code where writing to a will override data in b

var a = new Buffer('hello');
var b = new Buffer('something important')
a.length = 50;
a.fill('a')
console.log(b.toString());

Output:

aaaaaaaaaaaaaaaaaaa

Reading is also possible. Printing content of a will print also content of b.

var a = new Buffer('hello');
var b = new Buffer('something important')
a.length = 50;
console.log(a.toString());

Output:

hellosomething important�/�/

[vkurchatkin]

@hakovala buffers a really unsafe by design. Of course it's possible to make length non-writable using Object.defineProperty, but that implies performance hit. So, not modifying length is possibly the best option.

Similar issue #5378

[trevnorris]

Yes. .length is not meant to be changed, but it's not made read-only because the increase in construction time is actually quite significant.