linux-kernel - Re: [Nouveau] [PATCH] nv50_disp_chan_mthd: ensure mthd is not NULL

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Date:   Thu, 20 Feb 2020 12:32:45 -0500
From:   Ilia Mirkin <imirkin@...m.mit.edu>
To:     Frédéric Pierret 
        <frederic.pierret@...es-os.org>
Cc:     Ben Skeggs <bskeggs@...hat.com>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        nouveau <nouveau@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Nouveau] [PATCH] nv50_disp_chan_mthd: ensure mthd is not NULL

Hi Frédéric,

It appears Ben made his own version of this patch (probably based on
the one you added to the kernel bz), and it's already upstream:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.6-rc2&id=0e6176c6d286316e9431b4f695940cfac4ffe6c2

Cheers,

  -ilia

On Thu, Feb 20, 2020 at 12:19 PM Frédéric Pierret
<frederic.pierret@...es-os.org> wrote:
>
> Hi,
> Is anything missing here? How can I get this merged?
>
> Best regards,
> Frédéric Pierret
>
> On 2020-02-08 20:43, Frédéric Pierret wrote:
> > Pointer to structure array is assumed not NULL by default. It has
> > the consequence to raise a kernel panic when it's not the case.
> >
> > Basically, running at least a RTX2080TI on Xen makes a bad mmio error
> > which causes having 'mthd' pointer to be NULL in 'channv50.c'. From the
> > code, it's assumed to be not NULL by accessing directly 'mthd->data[0]'
> > which is the reason of the kernel panic. Simply check if the pointer
> > is not NULL before continuing.
> >
> > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=206299
> > Cc: stable@...r.kernel.org
> > Signed-off-by: Frédéric Pierret (fepitre) <frederic.pierret@...es-os.org>
> > ---
> >  drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c
> > index bcf32d92ee5a..50e3539f33d2 100644
> > --- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c
> > +++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c
> > @@ -74,6 +74,8 @@ nv50_disp_chan_mthd(struct nv50_disp_chan *chan, int debug)
> >
> >       if (debug > subdev->debug)
> >               return;
> > +     if (!mthd)
> > +             return;
> >
> >       for (i = 0; (list = mthd->data[i].mthd) != NULL; i++) {
> >               u32 base = chan->head * mthd->addr;
> >
>
> _______________________________________________
> Nouveau mailing list
> Nouveau@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/nouveau

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