linux-kernel - Re: [PATCH 0/3]: x86, fpu: unlazy

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]

Message-ID: <54CADF72.5070507@redhat.com>
Date:	Thu, 29 Jan 2015 20:33:38 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Dave Hansen <dave.hansen@...ux.intel.com>,
	Oleg Nesterov <oleg@...hat.com>
CC:	Suresh Siddha <sbsiddha@...il.com>,
	Andy Lutomirski <luto@...capital.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3]: x86, fpu: unlazy_fpu fixes/cleanups

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 01/29/2015 06:26 PM, Dave Hansen wrote:
> On 01/29/2015 01:56 PM, Oleg Nesterov wrote:
>> --- x/arch/x86/kernel/traps.c +++ x/arch/x86/kernel/traps.c @@
>> -313,7 +313,7 @@ dotraplinkage void do_bounds(struct pt_r * It is
>> not directly accessible, though, so we need to * do an xsave and
>> then pull it out of the xsave buffer. */ -
>> fpu_save_init(&tsk->thread.fpu); +	unlazy_fpu(tsk); xsave_buf =
>> &(tsk->thread.fpu.state->xsave);
> ...
>> bndcsr = get_xsave_addr(xsave_buf, XSTATE_BNDCSR);
> 
> Hmm, if the the thread was not using the FPU, and this fails to
> save anything in to the xsave_buf, what will bndcsr point to?

If the thread was not using the FPU, can we reach the
bound range exception?

I believe the MPX feature uses information in the xstate.

- -- 
All rights reversed
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1

iQEcBAEBAgAGBQJUyt9yAAoJEM553pKExN6D6U4H+QENaWW78N/A9MfdluF9j1c4
mLVjsna+PrdglRNMgZPIozD/V+aONiVbEvUYt2bGuBP7PaHdvasm+05/U+SJF37z
SxdjH0+1U+IZPycf0eGRkrFpZvUuegNzJyQFcvPltjRNHc7faDm3nJv+xdjDd9DX
NxcvexnjhkLpXvbEIOksv/41EMjyYtDBEWwenCANCLQaGyk4VJUxXqiZ0ivqtNJX
WuzVydvtDebWKPHF61qqtDCGkuuJvypWR6Wbgqe1McKqNgElT4c3f5QDLG45fKrw
YaiFzBGpeFEJtDe7XLCmdlp6xUGLL2SxFn5PVdyB1toHd+V6eN//QlwAOhDJPeA=
=HPaU
-----END PGP SIGNATURE-----
--
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/