Re: [PATCH] mm: Prevent mapping slab pages to userspace

[Andrew Morton]

On Fri, 25 Jan 2019 09:38:27 -0800 Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:

> It's never appropriate to map a page allocated by SLAB into userspace.
> A buggy device driver might try this, or an attacker might be able to
> find a way to make it happen.

It wouldn't surprise me if someone somewhere is doing this.  Rather
than mysteriously breaking their code, how about we emit a warning and
still permit it to proceed, for a while?