CVE-2026-68273

This CVE reveals a temporal ownership inversion in amdgpu's pstate management that goes beyond a simple missing lock. The original code captured the previous pstate at context initialization (amdgpu_ctx_init), but that state became stale long before context teardown (amdgpu_ctx_fini) because sysfs paths could mutate pstate in the intervening window. When the context exited, it blindly restored the stale captured state, silently clobbering any pstate changes made through sysfs in the interim. The deeper architectural flaw is that init-time state capture assumes a static ownership model in what is actually a dynamic, multi-source state machine. Sysfs is a public control plane—any privileged user can trigger a pstate override, and their requested state would be silently discarded when an unrelated context tears down. The fix restructures this into a clear ownership transfer model: the context saves the previous state only at the exact moment it takes over pstate control, and restores only if it still holds that ownership. Key actions for defenders: (1) verify that amdgpu_ctx_init() now properly acquires the stable_pstate_ctx_lock before capturing pstate state; (2) confirm the restore-on-exit logic validates ownership before performing any restore; (3) audit other amdgpu subsystems for similar init-time state capture patterns where runtime configuration paths (sysfs, ioctls) can interpose. The lock existed in the codebase but was scoped to the wrong entry points—it covered the obvious paths but missed amdgpu_ctx_init itself. The CVSS 7.8 appears conservative given that initialization-time UAFs can occur before ASLR settles and in paths reachable from relatively unprivileged contexts. Additionally, pstate corruption has multi-process blast radius on shared GPU hardware—the stale restore can propagate to hardware state that unrelated contexts depend on, potentially causing hangs or watchdog-triggered panics. Prioritize patching on multi-tenant GPU systems.

Reviewed through automated stages and approved by a human before publication.