Messages in this thread | | | Date | Mon, 21 May 2007 11:45:07 +0200 | From | Nick Piggin <> | Subject | Re: [rfc] increase struct page size?! |
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On Mon, May 21, 2007 at 11:12:59AM +0200, Helge Hafting wrote: > Andrew Morton wrote: > >On Sat, 19 May 2007 11:15:01 -0700 William Lee Irwin III > ><wli@holomorphy.com> wrote: > > > > > >>Much the same holds for the atomic_t's; 32 + PAGE_SHIFT is > >>44 bits or more, about as much as is possible, and one reference per > >>page per page is not even feasible. Full-length atomic_t's are just > >>not necessary. > >> > > > >You can overflow a page's refcount by mapping it 4G times. That requires > >32GB of pagetable memory. It's quite feasible with remap_file_pages(). > > > But do anybody ever need to do that? > Such an attack is easily thwarted by refusing to map it more > than, say 3G times?
That still allows you to DoS the page.
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