Linux Kernel EUVD-2026-39292

The flaw lives in the drm/xe DRM driver, which manages modern Intel discrete and integrated GPUs (Arc/DG2, Meteor Lake and later) via the GuC firmware microcontroller that arbitrates GPU context scheduling. 'userptr' VMAs let userspace back GPU virtual memory with ordinary process pages; when those pages are invalidated (e.g., munmap, migration, MMU notifier callbacks), the GPU's TLB must be flushed so it no longer references the old physical pages. That flush is performed as a side effect of the GPU context switch triggered when GuC processes a suspend. The reverted optimization (commit 8533051ce920) skipped the GuC suspend schedule toggle for idle queues, so in LR/preempt-fence VM mode the context switch - and therefore the TLB flush - never happened, leaving stale mappings. The root cause class is improper synchronization / missing invalidation of cached translations (no CWE was assigned in the source data); functionally it behaves like a stale-mapping/use-after-invalidation condition rather than the 'Authentication Bypass' label applied in the source tags.