linux-kernel - Re: [PATCH 1/1] x86/fpu: x86/fpu: avoid math_state_restore() without used_math() in __restore_xstate

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:	Mon, 9 Mar 2015 17:53:38 +0100
From:	Borislav Petkov <bp@...e.de>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Dave Hansen <dave.hansen@...el.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Pekka Riikonen <priikone@....fi>,
	Rik van Riel <riel@...hat.com>,
	Suresh Siddha <sbsiddha@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	Quentin Casasnovas <quentin.casasnovas@...cle.com>
Subject: Re: [PATCH 1/1] x86/fpu: x86/fpu: avoid math_state_restore() without
 used_math() in __restore_xstate_sig()

On Mon, Mar 09, 2015 at 05:24:04PM +0100, Oleg Nesterov wrote:
> Well, this is the same thinhg reported by Dave ;)

Am I the only one in thinking that this FPU thing went completely nuts?!
Just kill it all and let's start from scratch. :-P

> It is not fixed by Quentin's patch.
> 
> This patch "fixes" the problem in a sense that the kernel won't crash
> after restore_fpu_checking() triggers #GP. Before this patch
> do_general_protection()->fixup_exception() does not work in this case
> and the kernel panics.
> 
> But restore_fpu_checking() should not trigger #GP (and fail).

Right.

...

> But this too doesn't fix the problem: fpu_finit() is buggy on Dave's
> machine.

In talking about fpu_finit() - I still have two cleanup patches queued
from you:

http://git.kernel.org/cgit/linux/kernel/git/bp/bp.git/log/?h=tip-x86-fpu-2

Thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--
--
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/