Linux i915 GPU kernel driver (GTT TLB handling): MULTI-TENANT ISOLATION: Stale GPU TLB entries let the GPU keep reading

Impact

MULTI-TENANT ISOLATION: Stale GPU TLB entries let the GPU keep reading physical pages after they were unmapped and handed to somebody else. A tenant running crafted GPU code reads whatever the host recycled those pages into - other tenants' data, or kernel memory. This is a true cross-tenant memory disclosure on Intel GPU nodes, not a crash bug.

Who can reach it

Any local user or container with a DRM render node - i.e. any tenant that was scheduled a GPU. No privileged capability needed.

What to do

Update the kernel and reboot; the fix forces a full TLB flush on unbind, which costs GPU unbind throughput on memory-churning workloads. Drain the node - the driver cannot be swapped under live GPU jobs. Kernel-only, no firmware or microcode.

References