Re: [PATCH 1/3] uprobes: fix the usage of install_special_mapping()

[Andy Lutomirski]

On Thu, Jul 9, 2015 at 2:44 PM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> install_special_mapping(pages) expects that "pages" is the zero-
> terminated array while xol_add_vma() passes &area->page, this means
> that special_mapping_fault() can wrongly use the next member in
> xol_area (vaddr) as "struct page *".
>
> Fortunately, this area is not expandable so pgoff != 0 isn't possible
> (modulo bugs in special_mapping_vmops), but still this does not look
> good.
>

I fell for that awhile back, too, causing a bizarre HPET bug.

What zeroes pages[1]?

--Andy
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