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    SubjectRe: [RFC] [Patch 0/21] Non disruptive application core dump infrastructure
    Hello,

    On 12/14/2010 04:49 PM, Linus Torvalds wrote:
    > On Tue, Dec 14, 2010 at 1:52 AM, Suzuki K. Poulose <suzuki@in.ibm.com> wrote:
    >>
    >> This is series of patches implementing an infrastructure for capturing the core
    >> of an application without disrupting its process semantics.
    >>
    >> The infrastructure makes use of the freezer subsystem in kernel to freeze the
    >> threads and then collect the information to generate the core.
    >
    > This seems to be a fundamentally flawed approach.
    >
    >>From a security standpoint, it looks like a total disaster. A frozen
    > process is really hard to get rid of, so it looks like an obvious DoS
    > attack to just create lots of processes, then sneakily freeze them
    > all, and then laugh at the poor system admin who has no idea what's
    > going on. While frozen, the things are basically unkillable but look
    > entirely normal, no?

    I think a better way would be adding a ptrace attach which is nestable
    and doesn't have the nasty side effect caused by the interactions
    between the implicit SIGSTOP and group stop. As a preparation step, I
    posted a patchset to cleanup the interactions between ptrace and group
    stop which is being reviewed. Once we have a nestable ptrace attach,
    we should be able to simply adapt gcore(1) to use it and write out
    core dump from userland.

    Thanks.

    --
    tejun


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