linux-kernel - Re: [PATCH 3/3] x86: kernel base offset ASLR

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 05 Apr 2013 15:08:32 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Julien Tinnes <jln@...gle.com>
CC:	Ingo Molnar <mingo@...nel.org>, Kees Cook <keescook@...omium.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	Jarkko Sakkinen <jarkko.sakkinen@...el.com>,
	Matthew Garrett <mjg@...hat.com>,
	Matt Fleming <matt.fleming@...el.com>,
	Eric Northup <digitaleric@...gle.com>,
	Dan Rosenberg <drosenberg@...curity.com>,
	Will Drewry <wad@...omium.org>
Subject: Re: [PATCH 3/3] x86: kernel base offset ASLR

On 04/05/2013 03:06 PM, Julien Tinnes wrote:
> 
> Speaking of IDT, and to capture some off-thread discussion here, we
> should remember that the "SGDT" and "SIDT" instructions aren't
> privileged on x86, so user-land can leak these out without any way for
> the kernel to intercept that.
> 
> Adding their own random offsets to these two tables would be very
> useful. This could be done in a later patchset of course.
> 

Yes, if the GDT or IDT position is at all correlated to the kernel
position this is pointless.

	-hpa


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/