Re: [Qemu-devel] FPU x86 instructions error

[TeLeMan]

On Sat, May 25, 2013 at 5:39 AM, Clemens Kolbitsch
<address@hidden> wrote:
> Hi guys,
>
> we recently had an issue with running a program using FPU instructions
> to obtain the current EIP (basically a weird way of "call 0; pop eax")
> that was not working on QEMU (with TCG).
>
> Looking at the problem, we found this patch to be useful/fixing the issue:
>
> https://launchpadlibrarian.net/140457932/patch-qemu-1.5.0-fpip.diff
This patch is not working fully because the floating-point control
instructions do not change fpip.

>
> Looking through the DEVEL archives, I found this patch
>
> http://lists.nongnu.org/archive/html/qemu-devel/2011-06/msg01206.html
>
> that adds the FPU flags to the environment, but is only using them for KVM.
>
> I was wondering - since the above patch is rather old, you have
> probably come across it before - if there was a reason for not
> including it in QEMU (I checked in git:master and it's not applied).
> If there isn't, maybe it'd be worth re-considering :)
>
> thanks!
> -Clemens
>
>
> --
> Clemens Kolbitsch
> Security Researcher
> address@hidden
>
> Lastline, Inc.
> 6950 Hollister Avenue, Suite 101
> Goleta, CA 93117
>
> www.lastline.com
>