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    SubjectRe: [PATCH 0/6] kexec: A new system call to allow in kernel loading
    On Fri, 22 Nov 2013 05:34:03 -0800
    ebiederm@xmission.com (Eric W. Biederman) wrote:

    > Vivek Goyal <vgoyal@redhat.com> writes:

    > >> There is also a huge missing piece of this in that your purgatory is not
    > >> checking a hash of the loaded image before jumping too it. Without that
    > >> this is a huge regression at least for the kexec on panic case. We
    > >> absolutely need to check that the kernel sitting around in memory has
    > >> not been corrupted before we let it run very far.
    > >
    > > Agreed. This should not be hard. It is just a matter of calcualting
    > > digest of segments. I will store it in kimge and verify digest again
    > > before passing control to control page. Will fix it in next version.
    >
    > Nak. The verification needs to happen in purgatory.
    >
    > The verification needs to happen in code whose runtime environment is
    > does not depend on random parts of the kernel. Anything else is a
    > regression in maintainability and reliability.

    Hello Vivek,

    Just to be sure that you have not forgotten the following s390 detail:

    On s390 we first call purgatory with parameter "0" for doing the
    checksum test. If this fails, we can have as backup solution our
    traditional stand-alone dump. In case tha checksum test was ok,
    we call purgatory a second time with parameter "1" which then
    starts kdump.

    Could you please ensure that this mechanism also works after
    your rework.

    Best Regards,
    Michael



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