Executive brief
The Linux kernel's Panthor GPU driver manages graphics workqueues and job scheduling using fence synchronization primitives. A missing IRQ-safe lock variant could allow interrupt handlers from other kernel subsystems to access shared fence objects without proper locking, potentially causing data corruption or system instability in high-performance graphics workloads.
Technical details
The vulnerability is a missing IRQ-safe spinlock acquisition (spinlock_irqsave variant) in the Panthor DRM scheduler's fence lock handling. The fence_ctx.lock protects in-flight GPU jobs, but since dma_fence objects are shared across kernel subsystems, they may be accessed from hardware interrupt context (hardirq). The fix replaces standard spin_lock/spin_unlock calls with guard(spinlock_irqsave) and scoped_guard(spinlock_irqsave) macros to prevent interrupt-induced deadlocks. The vulnerability affects the panthor_sched.c component and the patch was applied in June 2026. No active exploitation has been reported.
Affected products
- Linux Linux kernel 5.x and later (drm/panthor driver)
Timeline
- 2026-08-15: disclosed
- 2026-06-25: patched: Upstream commit 778c57d624974e64535ef1c9d9b4d8e5066153f4