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Date: Thu, 26 Jul 2018 18:15:58 -0400
From: Steven Rostedt <>
To: Nick Desaulniers <>
Cc:, Kees Cook <>,,
 LKML <>,,,,
Subject: Re: [PATCH] tracing: do not leak kernel addresses

On Thu, 26 Jul 2018 09:52:11 -0700
Nick Desaulniers <> wrote:

> See the section "Kernel addresses" in
> Documentation/security/self-protection.  IIRC, the issue is that a
> process may have CAP_SYSLOG but not necessarily CAP_SYS_ADMIN (so it
> can read dmesg, but not necessarily issue a sysctl to change
> kptr_restrict), get compromised and used to leak kernel addresses,
> which can then be used to defeat KASLR.

But the code doesn't go to dmesg. It's only available
via /sys/kernel/debug/tracing/printk_formats which is only available
via root. Nobody else has access to that directory.

-- Steve

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