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    SubjectRe: [Security] [PATCH] proc: avoid information leaks to non-privileged processes

    * Matt Mackall <> wrote:

    > As to what's the appropriate sort of RNG for ASLR to use, finding
    > a balance between too strong and too weak is tricky. [...]

    In exec-shield i mixed 'easily accessible and fast' semi-random
    state to the get_random_int() result: xor-ed the cycle counter, the
    pid and a kernel address to it. That strengthened the result in a
    pretty practical way (without strengthening the theoretical
    randomless - each of those items are considered guessable) and does
    so without weakening the entropy of the random pool.

    As usual, it got objected to and removed during upstream review so
    the upstream code stands on a single foot only - which is an
    obviously bad idea.

    The thing is, it's very hard to argue for (and prove) security
    related complexity on an objective basis. ASLR was met with quite
    some upstream hostility, so it did not really get merged upstream,
    it barely managed to limp upstream.


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