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    SubjectRe: [PATCH] Make LIST_POISON less deadly
    On Sun 2008-05-18 18:38:14, Avi Kivity wrote:
    > The list macros use LIST_POISON1 and LIST_POISON2 as undereferencable
    > pointers in order to trap erronous use of freed list_heads. Unfortunately
    > userspace can arrange for those pointers to actually be dereferencable,
    > potentially turning an oops to an expolit.
    >
    > To avoid this allow architectures (currently x86_64 only) to override
    > the default values for these pointers with truly-undereferncable values.
    > This is easy on x86_64 as the virtual address space is smaller than
    > the range spanned by pointer values.

    "Security hole unless arch maintainer does _foo_" sounds
    scary. Especially when i386 is hard to fix...

    (And very nice catch, btw).
    Pavel

    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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