[PATCH xserver] glamor: Cannot use copies when accessing outside of composite source

Michel Dänzer michel at daenzer.net
Sat May 28 02:54:24 UTC 2016

On 28.05.2016 05:29, Keith Packard wrote:
> Michel Dänzer <michel at daenzer.net> writes:
>> From: Michel Dänzer <michel.daenzer at amd.com>
>> Commit b64108fa ("glamor: Check for composite operations which are
>> equivalent to copies") failed to copy conditions from exaComposite which
>> ensure that the composite operation doesn't access outside of the source
>> picture.
> I'm confused -- the region to be copied should already have been clipped
> to the source, so there shouldn't be any access outside of the source
> picture.

You know the details better than I do, but my understanding is that the
region can only be clipped to the destination in general, because
accessing source pictures outside of their boundaries is defined such
that it can change the contents of the destination.

Anyway, the fact is that this patch fixes a fair number of rendercheck

Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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