Linux kernel (drivers/gpu/drm/i915/gt): Compression (CCS) metadata attached to local memory was not cleared when the

Impact

Compression (CCS) metadata attached to local memory was not cleared when the memory was handed to a new owner, so a tenant receiving recycled VRAM inherits the previous tenant's compression state. The upstream fix is worded exactly that way - the kernel was leaking the CCS state from the previous user - which is residual-data exposure across workloads sharing a discrete Intel GPU.

Who can reach it

A tenant container holding /dev/dri/renderD* on a discrete Intel GPU allocates local memory that a previous tenant freed and reads it back with the compression state still attached. Purely local, unprivileged, no display or profiling access needed; only affects hosts with discrete Intel (lmem-capable) GPUs shared serially between workloads.

What to do

Boot a kernel carrying the i915 CCS-state fix below. Interim: do not recycle a GPU between tenants without a full device reset/scrub cycle, and prefer whole-device-per-tenant scheduling on discrete Intel cards until patched.

References