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SubjectRe: msync() bug
Andrea Arcangeli wrote:
>
> Wrong fix, `page' is just garbage if some non memory was mapped in
> userspace (like framebuffers or similar mmio regions were mapped etc..).

Now we're getting somewhere. Thanks. Tell me if this is right:


> if (VALID_PAGE(page)

If the physical address of the page is somewhere inside our
working RAM.

> !PageReserved(page)

And it's not a reserved page (discontigmem?)

> ptep_test_and_clear_dirty(ptep))

And if it was modified via this mapping

> + flush_tlb_page(vma, address);
> + set_page_dirty(page);

Question: What happens if a program mmap's a part of /dev/mem
which passes all of these tests? Couldn't it then pick some
arbitrary member of mem_map[] which may or may not have
a non-zero ->mapping?
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