linux-kernel - Re: [PATCH] Make math_state_restore() save and restore the interrupt flag

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 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:	Sat, 1 Feb 2014 17:38:27 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Suresh Siddha <sbsiddha@...il.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Nate Eldredge <nate@...tsmathematics.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	"the arch/x86 maintainers" <x86@...nel.org>,
	stable <stable@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Maarten Baert <maarten-baert@...mail.com>,
	Jan Kara <jack@...e.cz>, George Spelvin <linux@...izon.com>,
	Pekka Riikonen <priikone@....fi>
Subject: Re: [PATCH] Make math_state_restore() save and restore the interrupt flag

On Sat, Feb 1, 2014 at 5:35 PM, Suresh Siddha <sbsiddha@...il.com> wrote:
> On Sat, Feb 1, 2014 at 5:26 PM, H. Peter Anvin <hpa@...or.com> wrote:
>> Even "b" does that, no?
>
> oh right. It needs an else. only for non-eager fpu case we should do stts()

It definitely does not want an else, I think.

If tsk_used_math() is false, or if the FPU restore failed, we
*definitely* need that stts(). Otherwise we'd return to user mode with
random contents in the FP state, and let user mode muck around with
it.

No?

                     Linus
--
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/