From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
Subject: Re: [PATCH 2/3] drm/i915/sdvo: Robustify the
 dtd<->drm_mode conversions
Date: Tue, 10 Sep 2013 14:00:27 +0300
Message-ID: <20130910110027.GM11428@intel.com>
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To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
List-Id: intel-gfx@lists.freedesktop.org

On Tue, Sep 10, 2013 at 12:50:25PM +0200, Daniel Vetter wrote:
> On Tue, Sep 10, 2013 at 12:26 PM, Ville Syrj=E4l=E4
> <ville.syrjala@linux.intel.com> wrote:
> >>  static void intel_sdvo_get_mode_from_dtd(struct drm_display_mode * mo=
de,
> >>                                        const struct intel_sdvo_dtd *dt=
d)
> >>  {
> >> +     memset(mode, 0, sizeof(*mode));
> >
> > I have a theoretical worry that someone might end up calling this on a
> > mode that sits on some list or was actually allocated and has a proper
> > object id which we'd leak here.
> >
> > To make it totally safe you could populate a pristine mode struct and
> > use drm_mode_copy() to overwrite adjusted_mode. Assuming we're not so
> > short on stack space that our oversized mode struct would cause issues.
> > Other options would be to add some WARNs to catch wrongdoers, or embed
> > a temp mode for this purpose inside the intel_sdvo struct.
> =

> We can't really check for this since list_empty on stack garbage won't
> work too well, either. And e.g. ->get_config has the pipe config on
> the stack. So I think we just need to do review here. I also think the
> risk is pretty low, this is all used in internal structures around
> pipe_config, where the mode is never linked.

Well, another idea would be to add drm_mode_clear() what would do the
memset() but preserve the id and list head.

-- =

Ville Syrj=E4l=E4
Intel OTC