Re: [Qemu-devel] [PATCH] seccomp: check TSYNC host capability - Marc-André Lureau

From: "Marc-André Lureau" <marcandre.lureau@gmail.com>
To: Thomas Huth <thuth@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>,
	Eduardo Otubo <otubo@redhat.com>, QEMU <qemu-devel@nongnu.org>,
	Andrea Bolognani <abologna@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] seccomp: check TSYNC host capability
Date: Mon, 29 Apr 2019 15:49:22 +0200	[thread overview]
Message-ID: <CAJ+F1CKifW6Z=ZDK0j4Wgjb5mzCGLL+aNeP1UdB665y+Sodz5Q@mail.gmail.com> (raw)
In-Reply-To: <0942d4a4-f264-fd42-0b2d-994c331a000c@redhat.com>

Hi

On Mon, Apr 29, 2019 at 3:22 PM Thomas Huth <thuth@redhat.com> wrote:
>
> On 13/12/2018 04.24, David Gibson wrote:
> > On Thu, Aug 30, 2018 at 04:33:48PM +0200, Marc-André Lureau wrote:
> >> Remove -sandbox option if the host is not capable of TSYNC, since the
> >> sandbox will fail at setup time otherwise. This will help libvirt, for
> >> ex, to figure out if -sandbox will work.
> >>
> >> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> >
> > This seems to have introduced a regression, which I found when
> > preparing a ppc pull request.  Specifically when running with RHEL7 on
> > a POWER host, using "-sandbox off" which one of my tests did, causes a
> > cryptic error followed by a SEGV:
> >
> > $ ./ppc64-softmmu/qemu-system-ppc64 -sandbox off
> > qemu-system-ppc64: -sandbox off: There is no option group 'sandbox'
> > Segmentation fault
> > $ ./x86_64-softmmu/qemu-system-x86_64 -sandbox off
> > qemu-system-x86_64: -sandbox off: There is no option group 'sandbox'
> > Segmentation fault
> >
> > I think the problem is that while this wrapped one use of the sandbox
> > option group to produce a sensible error, it didn't do the same for
> > another call to qemu_opts_parse_noisily():
> >
> > (gdb) bt
> > #0  0x00000000105b36d8 in opts_parse (list=0x0, params=0x3ffffffffab5 "off", permit_abbrev=true, defaults=false, errp=0x3ffffffff080)
> >     at util/qemu-option.c:829
> > #1  0x00000000105b3b74 in qemu_opts_parse_noisily (list=<optimized out>, params=<optimized out>, permit_abbrev=<optimized out>) at util/qemu-option.c:890
> > #2  0x0000000010024964 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at vl.c:3589
> >
> > I'm guessing RHEL7 triggers it because that has a version of
> > libseccomp that doesn't support the feature needed to complete
> > registration (maybe on ppc host only; I haven't had a chance to try on
> > an x86 RHEL7 host).
>
> Andrea reported the same issue again today with QEMU v4.0 ...
> Marc-André, have you ever had another look into this issue?

Sorry, I thought this was already fixed and I forgot about it.

I just sent "[PATCH] vl: fix -sandbox parsing crash when seccomp
support is disabled".

thanks

-- 
Marc-André Lureau