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Date: Wed, 29 Nov 2017 10:07:27 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Linus Torvalds' <torvalds@...ux-foundation.org>, "Tobin C. Harding"
	<me@...in.cc>
CC: "kernel-hardening@...ts.openwall.com"
	<kernel-hardening@...ts.openwall.com>, "Jason A. Donenfeld"
	<Jason@...c4.com>, Theodore Ts'o <tytso@....edu>, Kees Cook
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 Heo" <tj@...nel.org>, Jordan Glover <Golden_Miller83@...tonmail.ch>, Greg KH
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	Radim Krcm√°r <rkrcmar@...hat.com>, "Linux Kernel Mailing
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	<netdev@...r.kernel.org>, David Miller <davem@...emloft.net>, "Stephen
 Rothwell" <sfr@...b.auug.org.au>, Andrey Ryabinin <aryabinin@...tuozzo.com>,
	Alexander Potapenko <glider@...gle.com>, Dmitry Vyukov <dvyukov@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: RE: [PATCH V11 4/5] vsprintf: add printk specifier %px

From: Linus Torvalds
> Sent: 29 November 2017 02:29
> 
> On Tue, Nov 28, 2017 at 6:05 PM, Tobin C. Harding <me@...in.cc> wrote:
> >
> >    Let's add specifier %px as a
> > clear, opt-in, way to print a pointer and maintain some level of
> > isolation from all the other hex integer output within the Kernel.
> 
> Yes, I like this model. It's easy and it's obvious ("'x' for hex"),
> and it gives people a good way to say "yes, I really want the actual
> address as hex" for if/when the hashed pointer doesn't work for some
> reason.

Remind me to change every %p to %px on kernels that support it.

Although the absolute values of pointers may not be useful, knowing
that two pointer differ by a small amount is useful.
It is also useful to know whether pointers are to stack, code, static
data or heap.

This change to %p is going to make debugging a nightmare.

	David

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