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    SubjectRe: [PATCH] mm: Prevent mapping slab pages to userspace
    On Tue, Jan 29, 2019 at 7:21 AM Andrew Morton <akpm@linux-foundation.org> wrote:
    >
    > On Fri, 25 Jan 2019 09:38:27 -0800 Matthew Wilcox <willy@infradead.org> 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?

    It seems like a fatal condition to me? There's nothing to check that
    such a page wouldn't get freed by the slab while still mapped to
    userspace, right?

    But I'll take warning over not checking. :)

    --
    Kees Cook

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