linux-kernel - Re: [PATCH V8 2/2] printk: hash addresses printed with %p

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Message-ID: <20171030200046.1f40a9dc@gandalf.local.home>
Date:   Mon, 30 Oct 2017 20:00:46 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Tobin C. Harding" <me@...in.cc>
Cc:     kernel-hardening@...ts.openwall.com,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Theodore Ts'o <tytso@....edu>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Tycho Andersen <tycho@...ker.com>,
        "Roberts, William C" <william.c.roberts@...el.com>,
        Tejun Heo <tj@...nel.org>,
        Jordan Glover <Golden_Miller83@...tonmail.ch>,
        Greg KH <gregkh@...uxfoundation.org>,
        Petr Mladek <pmladek@...e.com>, Joe Perches <joe@...ches.com>,
        Ian Campbell <ijc@...lion.org.uk>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <wilal.deacon@....com>,
        Chris Fries <cfries@...gle.com>,
        Dave Weinstein <olorin@...gle.com>,
        Daniel Micay <danielmicay@...il.com>,
        Djalal Harouni <tixxdz@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V8 2/2] printk: hash addresses printed with %p

On Tue, 31 Oct 2017 09:41:02 +1100
"Tobin C. Harding" <me@...in.cc> wrote:


> Cool. So I think we need
> 
>  	get_random_bytes(&ptr_key, sizeof(ptr_key));

You'll need to add a comment here to describe what ordering the memory
barrier is used against. That is, somewhere else there's something that
needs to see the "true" after the "get_random_bytes" update. Describe
it here.

-- Steve


> 	smp_mb();
>  	WRITE_ONCE(have_filled_random_ptr_key, true);
> 
> V10 to include this unless I have it wrong.
> 
> thanks,
> Tobin.