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    SubjectRe: [PATCH v4 10/10] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule
    On Tue, 31 May 2011, Andi Kleen wrote:
    > > +What: CONFIG_UNSAFE_VSYSCALLS (x86_64)
    > > +When: When glibc 2.14 or newer is ubitquitous. Perhaps mid-2012.
    > > +Why: Having user-executable code at a fixed address is a security problem.
    > > + Turning off CONFIG_UNSAFE_VSYSCALLS mostly removes the risk but will
    > > + make the time() function slower on glibc versions 2.13 and below.
    >
    > I disagree with this description (and the whole idea really)
    >
    > First it's time+gettimeofday+vgetcu, not just time.
    >
    > A more accurate description is
    >
    > "will make all x86-64 Linux programs written to the original pre
    > vDSO syscall ABI significantly slower"
    >
    > And the assumption that all world is using glibc is still as bad
    > as it was on the first po.st
    >
    > And it's still a bad idea. Especially since there's a much better
    > alternative anyways for the "security problem" which has none of
    > these drawbacks.

    How about posting an alternative patch?

    Thanks,

    tglx


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