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    SubjectRe: 2nd Linux kernel patch to remove stack exec
    Date
    Hi,

    > It's not really a problem -- everything should run just fine with my patch.
    > However, the patch will not prevent buffer overflow exploits for those
    > programs that use trampolines.
    >
    > This means that as long as libc5 is being used, most (if not all) privileged
    > processes will have stack execution permission disabled. :)
    >
    > As for glibc, maybe it is time to change it not to use trampolines?

    A patch which does this should now be in the glibc 2.1 development source.

    > > Admited trampolines are a stupid idea because their performance sucks
    > > on many architectures.
    >
    > AFAIK, they will cause some overhead for maintaining L1 code and data caches
    > coherency, since the stack frame is usually in the data cache -- resulting in
    > bad performance.

    We're talking about some hundred cycles or more ...

    Ralf

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