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SubjectRe: [patch 3/3] x86, mm: get ASLR work for hugetlb mappings

* akpm@linux-foundation.org <akpm@linux-foundation.org> wrote:

> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> Subject: x86, mm: get ASLR work for hugetlb mappings
>
> Matthew noticed that hugetlb doesn't participate in ASLR on x86-64. The
> reason is genereic hugetlb_get_unmapped_area() which is used on x86-64.
> It doesn't support randomization and use bottom-up unmapped area lookup,
> instead of usual top-down on x86-64.
>
> x86 has arch-specific hugetlb_get_unmapped_area(), but it's used only on
> x86-32.
>
> Let's use arch-specific hugetlb_get_unmapped_area() on x86-64 too. It
> fixes the issue and make hugetlb use top-down unmapped area lookup.

So the title and the changelog has typos (I counted three), which
makes me wonder how well this was tested.

To show/document the testing effort a before/after /proc/PID/maps
output showing hugetlb vma addresses would be nice, showing that ASLR
didn't work before and that it works adequately after the patch.

A word about the range and granularity of randomization in the typical
case would be nice as well.

Thanks,

Ingo


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