Linux kernel (drivers/gpu/drm/xe): The per-client memory accounting walks buffer-object state (TTM resource, tt pages)

Impact

The per-client memory accounting walks buffer-object state (TTM resource, tt pages) with no lock and no reference held. A tenant that keeps BOs churning while its fdinfo is read gets the kernel to follow freed pointers - use-after-free and NULL dereference in kernel context, the usual starting point for a container escape.

Who can reach it

Tenant holding /dev/dri/renderD* on Intel xe, plus anything that reads /proc/<pid>/fdinfo for that DRM fd - which the tenant can do to itself, and which fleet GPU-telemetry agents do continuously across tenants. One thread allocates and evicts BOs while the other reads fdinfo. No capabilities needed.

What to do

Update to a kernel with the fix (stable commits below; no fixed_in published). Interim: stop any fleet agent that scrapes DRM fdinfo on xe nodes - it does not remove the self-triggered path but it removes the cross-tenant one.

References