Re: [PATCH] drm/core: Fix ordering in drm_mode_config_cleanup.

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Mar 22, 2016 at 04:08:39PM +0100, Maarten Lankhorst wrote:
> Op 22-03-16 om 15:58 schreef Ville Syrjälä:
> > On Tue, Mar 22, 2016 at 03:42:14PM +0100, Maarten Lankhorst wrote:
> >> __drm_atomic_helper_plane_destroy_state calls
> >> drm_framebuffer_unreference, which means that if drm_framebuffer_free
> >> is called before plane->destroy freed memory will be accessed.
> >>
> >> A similar case happens for the blob list, which was freed before the
> >> crtc state was, resulting in the unreference_blob from crtc_destroy_state
> >> pointing to garbage memory causing another opportunity for a GPF.
> >>
> >> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> >> ---
> >>  drivers/gpu/drm/drm_crtc.c | 18 +++++++++---------
> >>  1 file changed, 9 insertions(+), 9 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> >> index 51c5a00ffdff..5a13b1afccbe 100644
> >> --- a/drivers/gpu/drm/drm_crtc.c
> >> +++ b/drivers/gpu/drm/drm_crtc.c
> >> @@ -5958,6 +5958,15 @@ void drm_mode_config_cleanup(struct drm_device *dev)
> >>  		drm_property_destroy(dev, property);
> >>  	}
> > And what about props? Any chance of explosion due to those being gone?
> >
> Not as far as I'm aware of.
> 
> If you use something like a crtc_x property, only the value gets written to crtc_state, the value is an int that would still be valid.

I was too lazy to confirm this for all drivers. But at least i915 looked
clean on that front. So

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> 
> ~Maarten

-- 
Ville Syrjälä
Intel OTC
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