linux-kernel - Re: [PATCH 4/8] x86: Add support for rd/wr fs/gs base

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, 10 Apr 2015 13:41:25 -0700
From:	Andi Kleen <ak@...ux.intel.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Andi Kleen <andi@...stfloor.org>, X86 ML <x86@...nel.org>,
	Andrew Lutomirski <luto@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 4/8] x86: Add support for rd/wr fs/gs base

> It wouldn't take any additional memory at all.  Currently we have 8k
> of "debug" stack which is really two 4k pieces, and you're putting the
> kernel gs base in the bottom word.  I'm suggesting that you duplicate
> the kernel gs base at the bottom work and the bottom word + 4k.  We
> already have a hard limit of 4k of debug stack because of the IST
> shift mechanism -- it really is two separate 4k stacks, not one 8k
> stack.

Seems like a hack. What happens if we add an uneven number of stacks?

Just handling it in the code is simple enough.


-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only
--
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/