linux-kernel - Re: [BUG] perf: bogus correlation of kernel symbols

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Message-ID: <BANLkTi=EfPMQ4Z7+_SrKAeOYHfDC6t9vyQ@mail.gmail.com>
Date:	Fri, 13 May 2011 00:15:41 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Dave Jones <davej@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Stephane Eranian <eranian@...gle.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] perf: bogus correlation of kernel symbols

On Fri, May 13, 2011 at 12:07 AM, Dave Jones <davej@...hat.com> wrote:
> On Thu, May 12, 2011 at 11:50:23PM +0200, Ingo Molnar wrote:
>
>  > Dunno, i would not couple them necessarily - certain users might still have
>  > access to kernel symbols via some other channel - for example the System.map.
>
> That always made this security by obscurity feature seem pointless for the bulk
> of users to me. Given the majority are going to be running distro kernels,
> anyone can find those addresses easily no matter how hard we hide them on the
> running system.

> Unless we were somehow introduced randomness into where we unpack the kernel
> each boot, and using System.map as a table of offsets instead of absolute addresses.
>
Good point about System.map! Even if /proc/kallsyms contains zero
addresses, I can
still get them from /boot/System.map which is readable by everyone, I
think. It does
not contain the modules addresses, but you have the core functions, unless I am
somehow mistaken.
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