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    SubjectRe: [GIT PULL] hash addresses printed with %p
    On Wed, Nov 29, 2017 at 11:22:29AM -0800, Linus Torvalds wrote:
    > On Tue, Nov 28, 2017 at 8:59 PM, Tobin C. Harding <me@tobin.cc> wrote:
    > >
    > > git://github.com/tcharding/linux.git tags/printk-hash-pointer-4.15-rc2
    >
    > Bah.

    Sorry for creating extra work for you.

    > What I didn't realize until after pulling this and testing, is that it
    > completely breaks '%pK'.

    If you haven't wasted enough time on this can you tell me what you mean
    by 'completely breaks %pK'?

    If I am at fault I do not want to repeat the same mistake again.

    I have just re-run my tests and it passes so something must be wrong
    with my tests or method. I wrote a module to print various pointers
    using %pK (same module that tests the hashing stuff), built the kernel
    with the patch set applied then booted the kernel in a VM and inserted
    the module (kptr_restrict==0). Confirmed that addresses were
    displayed. Then I set kptr_restrict to 2 and re-inserted the
    module. Confirmed that pointers were zeroed out when printed with %pK.

    > We've marked various sensitive pointers with %pK, but that is now
    > _less_ secure than %p is, since it doesn't do the hashing because of
    > how you refactored the %pK code out of 'pointer()' into its own
    > function.

    Oh, I think I get it. You mean that it is better to hash the address for
    %pK (kpt_restrict==0) than to zero it out?

    > So now %pK ends up using the plain "number()" function. Reading
    > through the series I hadn't noticed that the refactoring ended up
    > messing with that.
    >
    > I'll fix it up somehow.

    (I saw the fix in the next email)

    thanks,
    Tobin.

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