The SiS DRI client driver (sis_screen.c) forgets to clear an engine packet, which might therefore contain random data when sent to the engine. The possible consequences are self-explainatory. Fix is in MESA, see http://cvs.freedesktop.org/mesa/Mesa/src/mesa/drivers/dri/sis/sis_screen.c?r1=1.11.2.1&r2=1.11.2.2 (Why is there no "MESA" category for "component"?)
fixed with Mesa import
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