From: "H. Peter Anvin" <hpa@zytor.com>
To: "H. Peter Anvin" <hpa@linux.intel.com>,
Andrew Lutomirski <amluto@gmail.com>
Cc: comex <comexk@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Alexander van Heukelum <heukelum@fastmail.fm>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Borislav Petkov <bp@alien8.de>,
Arjan van de Ven <arjan.van.de.ven@intel.com>,
Brian Gerst <brgerst@gmail.com>,
Alexandre Julliard <julliard@winehq.com>,
Andi Kleen <andi@firstfloor.org>,
Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE*
Date: Mon, 28 Apr 2014 21:36:54 -0700 [thread overview]
Message-ID: <535F2C66.9090902@zytor.com> (raw)
In-Reply-To: <535F205F.9040101@zytor.com>
On 04/28/2014 08:45 PM, H. Peter Anvin wrote:
>
> OK, so I found a bug in ldttest.c -- it sets CS to an LDT segment, but
> it never sets SS to an LDT segment. This means that it should really
> have zero footprint versus the espfix code, and implies that we instead
> have another bug involved. Why the espfix code should have any effect
> whatsoever is a mystery, however... if it indeed does?
>
> I have uploaded a fixed ldttest.c, but it seems we might be chasing more
> than that...
>
With the test fixed, the bug was easy to find: we can't compare against
__KERNEL_DS in the doublefault handler, because both SS and the image on
the stack have the stack segment set to zero (NULL).
With that both ldttest and run16 pass with the doublefault code, even
with randomization turned back on.
I have pushed out the fix.
There are still things that need fixing: we need to go through the
espfix path even when returning from NMI/MC (which fortunately can't
nest with taking an NMI/MC on the espfix path itself, since in that case
we will have been interrupted while running in the kernel with a kernel
stack.)
(Cc: Rostedt because of the NMI issue.)
-hpa
next prev parent reply other threads:[~2014-04-29 4:38 UTC|newest]
Thread overview: 136+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-11 17:36 [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels tip-bot for H. Peter Anvin
2014-04-11 18:12 ` Andy Lutomirski
2014-04-11 18:20 ` H. Peter Anvin
2014-04-11 18:27 ` Brian Gerst
2014-04-11 18:29 ` H. Peter Anvin
2014-04-11 18:35 ` Brian Gerst
2014-04-11 21:16 ` Andy Lutomirski
2014-04-11 21:24 ` H. Peter Anvin
2014-04-11 21:53 ` Andy Lutomirski
2014-04-11 21:59 ` H. Peter Anvin
2014-04-11 22:15 ` Andy Lutomirski
2014-04-11 22:18 ` H. Peter Anvin
2014-04-13 4:20 ` H. Peter Anvin
2014-04-12 23:26 ` Alexander van Heukelum
2014-04-12 23:31 ` H. Peter Anvin
2014-04-12 23:49 ` Alexander van Heukelum
2014-04-13 0:03 ` H. Peter Anvin
2014-04-13 1:25 ` Andy Lutomirski
2014-04-13 1:29 ` Andy Lutomirski
2014-04-13 3:00 ` H. Peter Anvin
2014-04-11 21:34 ` Linus Torvalds
2014-04-11 18:41 ` Linus Torvalds
2014-04-11 18:45 ` Brian Gerst
2014-04-11 18:50 ` Linus Torvalds
2014-04-12 4:44 ` Brian Gerst
2014-04-12 17:18 ` H. Peter Anvin
2014-04-12 19:35 ` Borislav Petkov
2014-04-12 19:44 ` H. Peter Anvin
2014-04-12 20:11 ` Borislav Petkov
2014-04-12 20:34 ` Brian Gerst
2014-04-12 20:59 ` Borislav Petkov
2014-04-12 21:13 ` Brian Gerst
2014-04-12 21:40 ` Borislav Petkov
2014-04-14 7:21 ` Ingo Molnar
2014-04-14 9:44 ` Borislav Petkov
2014-04-14 9:47 ` Ingo Molnar
2014-04-12 21:53 ` Linus Torvalds
2014-04-12 22:25 ` H. Peter Anvin
2014-04-13 2:56 ` Andi Kleen
2014-04-13 3:02 ` H. Peter Anvin
2014-04-13 3:13 ` Linus Torvalds
2014-04-12 20:29 ` Brian Gerst
2014-04-14 7:48 ` Alexandre Julliard
2014-05-07 9:18 ` Sven Joachim
2014-05-07 10:18 ` Borislav Petkov
2014-05-07 16:57 ` Linus Torvalds
2014-05-07 17:09 ` H. Peter Anvin
2014-05-07 17:50 ` Alexandre Julliard
2014-05-08 6:43 ` Sven Joachim
2014-05-08 13:50 ` H. Peter Anvin
2014-05-08 20:13 ` H. Peter Anvin
2014-05-08 20:40 ` H. Peter Anvin
2014-05-12 13:16 ` Josh Boyer
2014-05-12 16:52 ` H. Peter Anvin
2014-05-14 23:43 ` [tip:x86/urgent] x86-64, modify_ldt: Make support for 16-bit segments a runtime option tip-bot for Linus Torvalds
2014-04-11 18:46 ` [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels H. Peter Anvin
2014-04-14 7:27 ` Ingo Molnar
2014-04-14 15:45 ` H. Peter Anvin
2014-04-13 2:54 ` Andi Kleen
2014-04-21 22:47 ` [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE* H. Peter Anvin
2014-04-21 23:19 ` Andrew Lutomirski
2014-04-21 23:29 ` H. Peter Anvin
2014-04-22 0:37 ` Andrew Lutomirski
2014-04-22 0:53 ` H. Peter Anvin
2014-04-22 1:06 ` Andrew Lutomirski
2014-04-22 1:14 ` H. Peter Anvin
2014-04-22 1:28 ` Andrew Lutomirski
2014-04-22 1:47 ` H. Peter Anvin
2014-04-22 1:53 ` Andrew Lutomirski
2014-04-22 11:23 ` Borislav Petkov
2014-04-22 14:46 ` Borislav Petkov
2014-04-22 16:03 ` Andrew Lutomirski
2014-04-22 16:10 ` H. Peter Anvin
2014-04-22 16:33 ` Andrew Lutomirski
2014-04-22 16:43 ` Linus Torvalds
2014-04-22 17:00 ` Andrew Lutomirski
2014-04-22 17:04 ` Linus Torvalds
2014-04-22 17:11 ` Andrew Lutomirski
2014-04-22 17:15 ` H. Peter Anvin
2014-04-23 9:54 ` One Thousand Gnomes
2014-04-23 15:53 ` H. Peter Anvin
2014-04-23 17:08 ` Andrew Lutomirski
2014-04-23 17:16 ` H. Peter Anvin
2014-04-23 17:25 ` Andrew Lutomirski
2014-04-23 17:28 ` H. Peter Anvin
2014-04-23 17:45 ` Andrew Lutomirski
2014-04-22 17:19 ` Linus Torvalds
2014-04-22 17:29 ` H. Peter Anvin
2014-04-22 17:46 ` Andrew Lutomirski
2014-04-22 17:59 ` H. Peter Anvin
2014-04-22 18:03 ` Brian Gerst
2014-04-22 18:06 ` H. Peter Anvin
2014-04-22 18:17 ` Brian Gerst
2014-04-22 18:51 ` H. Peter Anvin
2014-04-22 19:55 ` Brian Gerst
2014-04-22 20:17 ` H. Peter Anvin
2014-04-22 23:08 ` Brian Gerst
2014-04-22 23:39 ` Andi Kleen
2014-04-22 23:40 ` H. Peter Anvin
2014-04-22 17:11 ` H. Peter Anvin
2014-04-22 17:26 ` Borislav Petkov
2014-04-22 17:29 ` Andrew Lutomirski
2014-04-22 19:27 ` Borislav Petkov
2014-04-23 6:24 ` H. Peter Anvin
2014-04-23 8:57 ` Alexandre Julliard
2014-04-22 17:09 ` H. Peter Anvin
2014-04-22 17:20 ` Andrew Lutomirski
2014-04-22 17:24 ` H. Peter Anvin
2014-04-22 11:25 ` Borislav Petkov
2014-04-23 1:17 ` H. Peter Anvin
2014-04-23 1:23 ` Andrew Lutomirski
2014-04-23 1:42 ` H. Peter Anvin
2014-04-23 14:24 ` Boris Ostrovsky
2014-04-23 16:56 ` H. Peter Anvin
2014-04-28 13:04 ` Konrad Rzeszutek Wilk
2014-04-25 21:02 ` Konrad Rzeszutek Wilk
2014-04-25 21:16 ` H. Peter Anvin
2014-04-24 4:13 ` comex
2014-04-24 4:53 ` Andrew Lutomirski
2014-04-24 22:24 ` H. Peter Anvin
2014-04-24 22:31 ` Andrew Lutomirski
2014-04-24 22:37 ` H. Peter Anvin
2014-04-24 22:43 ` Andrew Lutomirski
2014-04-28 23:05 ` H. Peter Anvin
2014-04-28 23:08 ` H. Peter Anvin
2014-04-29 0:02 ` Andrew Lutomirski
2014-04-29 0:15 ` H. Peter Anvin
2014-04-29 0:20 ` Andrew Lutomirski
2014-04-29 2:38 ` H. Peter Anvin
2014-04-29 2:44 ` H. Peter Anvin
2014-04-29 3:45 ` H. Peter Anvin
2014-04-29 3:47 ` H. Peter Anvin
2014-04-29 4:36 ` H. Peter Anvin [this message]
2014-04-29 7:14 ` H. Peter Anvin
2014-04-25 12:02 ` Pavel Machek
2014-04-25 21:20 ` H. Peter Anvin
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