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Message-ID: <1508217608.6530.20.camel@perches.com>
Date: Mon, 16 Oct 2017 22:20:08 -0700
From: Joe Perches <joe@...ches.com>
To: "Tobin C. Harding" <me@...in.cc>, kernel-hardening@...ts.openwall.com
Cc: 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>, Ian Campbell <ijc@...lion.org.uk>, Sergey
Senozhatsky <sergey.senozhatsky@...il.com>, Catalin Marinas
<catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Steven
Rostedt <rostedt@...dmis.org>, 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 v2] printk: hash addresses printed with %p
On Tue, 2017-10-17 at 15:52 +1100, Tobin C. Harding wrote:
> Currently there are many places in the kernel where addresses are being
> printed using an unadorned %p. Kernel pointers should be printed using
> %pK allowing some control via the kptr_restrict sysctl. Exposing addresses
> gives attackers sensitive information about the kernel layout in memory.
>
> We can reduce the attack surface by hashing all addresses printed with
> %p. This will of course break some users, forcing code printing needed
> addresses to be updated.
>
> For what it's worth, usage of unadorned %p can be broken down as follows
>
> git grep '%p[^KFfSsBRrbMmIiEUVKNhdDgCGO]' | wc -l
Not really.
There are many asm uses included there
I think a better grep is:
$ git grep -E '%p[^A-Za-z0-9]' | cut -f1 -d"/" | sort | uniq -c
1084 arch
20 block
10 crypto
32 Documentation
8121 drivers
1221 fs
143 include
101 kernel
69 lib
100 mm
1510 net
40 samples
7 scripts
11 security
166 sound
152 tools
2 virt
> arch: 2512
arch is especially overestimated.
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