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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Wed, 11 Oct 2017 22:09:20 +0200
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Subject: Re: [PATCH 0/3] add %pX specifier
To: "Tobin C. Harding" <me@tobin.cc>
Cc: kernel-hardening@lists.openwall.com, kvm@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>, Paolo Bonzini <pbonzini@redhat.com>,
        Tycho Andersen <tycho@docker.com>,
        "Roberts, William C" <william.c.roberts@intel.com>,
        Tejun Heo <tj@kernel.org>,
        Jordan Glover <Golden_Miller83@protonmail.ch>,
        Greg KH <gregkh@linuxfoundation.org>, Petr Mladek <pmladek@suse.com>,
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        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
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Hi Tobin,

On Wed, Oct 11, 2017 at 1:09 AM, Tobin C. Harding <me@tobin.cc> wrote:
>
>   +        hashval = hash_three_words(
>   +                (unsigned long)ptr,
>   +                (unsigned long)ptr >> 16 >> 16,
>   +                boot_time_random_int);

This is most likely not what you want to be using. Take a look at the
siphash_* set of functions. If you're just hashing 1 64-bit pointer
with some secret, use siphash_1u64, for example. That's the right
interface for this purpose.

Regards,
Jason