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    SubjectRe: two things

    Andi Kleen writes:
    > linux kernel account <linker@nightshade.z.ml.org> writes:

    >> I want to point out that I have offered cash for someone to
    >> find an exploit that still works with no-exec stack...

    Since nobody collected, the patch is quite good.

    >> Yes, it's still possible BUT very difficult. The hack must either
    >> look like a trampolene or be in an app where a tram is occuring..
    >
    > Writing that exploit it pretty easy. You just have to guess the
    > address of a
    >
    > exec("/bin/sh");
    >
    > code fragment in libc (e.g. in system()) or in the program itself.
    > Then put this address on the stack and wait for the program to
    > jump to it.

    You'd think so, but some versions of the patch have a solution.
    There are actually 2 solutions:

    1. Randomize the stack and/or library location.
    (and of course failed exploits get logged)

    2. Map the library with a '\0' in the address.
    It is impossible to get such an address past strcpy().

    Anyway, this is an imperfect world. The patch is good.


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