linux-kernel - Re: nvdimm crash at boot

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Message-ID: <CAGXu5jKrhvUduv_XUYF94YM=bBfPGNkPrZ_EkvRKB0pDY_6uOw@mail.gmail.com>
Date:   Tue, 8 Jan 2019 15:55:42 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Dave Jiang <dave.jiang@...el.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: nvdimm crash at boot

On Tue, Jan 8, 2019 at 3:54 PM Dan Williams <dan.j.williams@...el.com> wrote:
>
> On Tue, Jan 8, 2019 at 3:34 PM Kees Cook <keescook@...omium.org> wrote:
> >
> > On Tue, Jan 8, 2019 at 3:28 PM Dan Williams <dan.j.williams@...el.com> wrote:
> > > Ah, thanks for the report! The key difference is that you don't define
> > > a "label area", so the driver bails out early and never initializes
> > > the security state.
> > >
> > > This should fix it up.
> > >
> > > diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
> > > index 4890310df874..636cdb06ee17 100644
> > > --- a/drivers/nvdimm/dimm_devs.c
> > > +++ b/drivers/nvdimm/dimm_devs.c
> > > @@ -514,7 +514,7 @@ static umode_t nvdimm_visible(struct kobject
> > > *kobj, struct attribute *a, int n)
> > >
> > >         if (a != &dev_attr_security.attr)
> > >                 return a->mode;
> > > -       if (nvdimm->sec.state < 0)
> > > +       if (!nvdimm->sec.ops || nvdimm->sec.state < 0)
> > >                 return 0;
> > >         /* Are there any state mutation ops? */
> > >         if (nvdimm->sec.ops->freeze || nvdimm->sec.ops->disable
> >
> > Okay, cool. I wasn't sure if that test needed a deeper check. :)
> >
> > Fixes: 37833fb7989a9 ("acpi/nfit, libnvdimm: Add freeze security
> > support to Intel nvdimm")
> > Tested-by: Kees Cook <keescook@...omium.org>
> >
>
> Actually, looking closer this should have been avoided by the fact
> that __nvdimm_create() initializes the security state early and that
> nvdimm->sec.state should have saved us.
>
> I'll dig a bit deeper with your qemu config.

Maybe something goes weird with pstore stealing the region?

-- 
Kees Cook