From: Pavel Machek <pavel@ucw.cz>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Timur Tabi <timur@kernel.org>, Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
willy@infradead.org, akpm@linux-foundation.org,
torvalds@linux-foundation.org, roman.fietze@magna.com,
keescook@chromium.org, john.ogness@linutronix.de,
akinobu.mita@gmail.com
Subject: Re: [PATCH] lib/vsprintf: make-printk-non-secret printks all addresses as unhashed
Date: Thu, 4 Feb 2021 22:49:44 +0100 [thread overview]
Message-ID: <20210204214944.GA13103@amd> (raw)
In-Reply-To: <20210204155423.2864bf4f@gandalf.local.home>
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Hi!
> Pavel Machek <pavel@ucw.cz> wrote:
>
> > > + pr_warn("** Kernel memory addresses are exposed, which may **\n");
> > > + pr_warn("** compromise security on your system. **\n");
> >
> > This is lies, right? And way too verbose.
>
> Not really. More of an exaggeration than a lie. And the verbosity is
> to
Well... security is _not_ compromised but robustness against kernel
bugs is reduced. It should not exaggerate.
> make sure it's noticed by those that shouldn't have it set. This works well
> for keeping trace_printk() out of production kernels. Why do you
> care
So if we want people to see it, we up the severity, right? Like
pr_err()... Distro kernels have quiet, anyway...
Lets take a look for what we say for _real_ problems:
[ 0.544757] Spectre V1 : Mitigation: usercopy/swapgs barriers and
__user pointer sanitiza
tion
[ 0.544876] Spectre V2 : Mitigation: Full generic retpoline
[ 0.544961] Spectre V2 : Spectre v2 / SpectreRSB mitigation:
Filling RSB on context switc
h
[ 0.545064] L1TF: System has more than MAX_PA/2 memory. L1TF
mitigation not effective.
[ 0.545163] L1TF: You may make it effective by booting the kernel
with mem=2147483648 par
ameter.
[ 0.545281] L1TF: However, doing so will make a part of your RAM
unusable.
[ 0.545374] L1TF: Reading
https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html
might help you decide.
This machine is insecure. Yet I don't see ascii-art *** all around..
"Kernel memory addresses are exposed, which is bad for security."
would be quite enough, I'd say...
Best regards,
Pavel
--
http://www.livejournal.com/~pavelmachek
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next prev parent reply other threads:[~2021-02-04 21:49 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 20:18 Timur Tabi
2021-02-02 21:52 ` Kees Cook
2021-02-02 22:19 ` Timur Tabi
2021-02-02 22:34 ` Steven Rostedt
2021-02-02 22:51 ` Linus Torvalds
2021-02-03 18:53 ` Kees Cook
2021-02-04 20:48 ` Pavel Machek
2021-02-04 20:54 ` Steven Rostedt
2021-02-04 21:49 ` Pavel Machek [this message]
2021-02-04 21:59 ` Timur Tabi
2021-02-04 22:06 ` Steven Rostedt
2021-02-04 22:11 ` Pavel Machek
2021-02-04 22:17 ` Kees Cook
2021-02-04 22:20 ` Timur Tabi
2021-02-04 22:51 ` Pavel Machek
2021-02-04 22:57 ` Pavel Machek
2021-02-04 22:05 ` Steven Rostedt
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