[Intel-gfx] [PATCH 1/2] drm/core: Preserve the framebuffer after removing it.

Tvrtko Ursulin tvrtko.ursulin at linux.intel.com
Wed Sep 9 08:18:02 PDT 2015

On 09/09/2015 04:04 PM, Daniel Vetter wrote:
> On Wed, Sep 09, 2015 at 03:51:50PM +0100, Tvrtko Ursulin wrote:
>> Hi,
>> On 09/09/2015 03:40 PM, Maarten Lankhorst wrote:
>>> Previously RMFB and fd close chose to disable any plane that had
>>> an active framebuffer from this file. If it was a primary plane the
>>> crtc was disabled. However the fbdev code or any system compositor
>>> should restore the planes anyway so there's no need to do it twice.
>>> The old fb_id is zero'd, so there's no danger of being able to
>>> restore the fb from fb_id.
>> What does this mean, say if the compositor dies last frame will remain on
>> the screen?
> Yes, and the commit message should mention that. It should also mention
> that other applications can't get at the data since we clear fb id still,
> so no information leak there.

Perhaps I replied to the wrong patch from the series.

Why is all this needed anyway? It sound pretty undesirable from the 
security point of view to me. If it is exploitable to leave something 
sensitive on screen that's not good.



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