linux-kernel - Re: [PATCH 02/19] x86, fpu: Wrap get_xsave

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:	Thu, 28 May 2015 07:45:18 -0700
From:	Dave Hansen <dave@...1.net>
To:	Ingo Molnar <mingo@...nel.org>
CC:	linux-kernel@...r.kernel.org, x86@...nel.org, tglx@...utronix.de,
	dave.hansen@...ux.intel.com, oleg@...hat.com, bp@...en8.de,
	riel@...hat.com, sbsiddha@...il.com, luto@...capital.net,
	mingo@...hat.com, hpa@...or.com, fenghua.yu@...el.com
Subject: Re: [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer

On 05/28/2015 01:41 AM, Ingo Molnar wrote:
> What you want here is to make the (in-memory) FPU state valid and current, before 
> reading it, and the function to use for that is fpu__activate_fpstate_read() 
> (available in the latest tip:x86/fpu tree).

Do we really want to unconditionally activate the FPU?

Let's say supporting MPX didn't require eager mode and someone called
get_xsave_addr().  We would ideally want to keep the FPU inactive and
just return NULL.  Right?
--
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/