CVE-2026-72388 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/panthor: Always use the IRQ-safe variant when acquiring the fence lock
Since dma_fence objects can be shared with other subsystems, they may be accessed from hardirq context in those drivers, and we have to take that into account by also using the IRQ-safe variant when acquiring the lock.
While at it, switch to the guard model.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/15/2026
This vulnerability resides within the linux kernel's direct rendering manager subsystem specifically affecting the panthor driver implementation. The issue stems from improper locking mechanisms when handling dma_fence objects which are critical synchronization primitives used across multiple kernel subsystems. These fence objects serve as lightweight synchronization mechanisms that track the completion of GPU operations and can be accessed by various drivers and components throughout the system. The vulnerability manifests when the driver attempts to acquire a lock protecting these fence objects without considering that they might be accessed from interrupt context, specifically hardirq context where standard locking primitives would lead to deadlocks or system instability.
The technical flaw involves the use of non-IRQ-safe locking mechanisms when acquiring fence locks in the drm/panthor subsystem. When dma_fence objects are shared across different kernel subsystems, there exists a possibility that they may be accessed from hardirq context by other drivers or kernel components. Standard spinlocks and mutexes used in the original implementation do not account for the interrupt context requirements, creating a potential race condition scenario where lock acquisition could fail or cause system crashes. This represents a classic violation of proper locking hierarchy principles where kernel developers must consider all possible execution contexts when implementing synchronization primitives.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially critical system stability issues. When dma_fence objects are accessed from hardirq context, using non-IRQ-safe locks can result in system deadlocks where the interrupt handler attempts to acquire a lock that is already held by a process running at normal priority levels. This scenario can lead to complete system hangs or kernel oops, particularly when multiple subsystems attempt to synchronize operations simultaneously. The vulnerability affects systems utilizing panthor GPU drivers and could be exploited by malicious actors to cause denial of service conditions or potentially gain unauthorized access through carefully crafted interrupt sequences.
The remediation approach involves transitioning from standard locking mechanisms to IRQ-safe variants when acquiring fence locks, specifically implementing the guard model pattern for proper synchronization. This change ensures that all lock acquisitions involving dma_fence objects are compatible with both normal process context and hardirq context execution paths. The switch to the guard model provides additional protection by ensuring proper lock ordering and preventing potential deadlocks through structured locking patterns that explicitly account for interrupt contexts. This implementation follows established kernel security best practices and aligns with common vulnerabilities and exposures (cwe) categories related to improper locking and race conditions in kernel drivers.
The vulnerability demonstrates a clear adherence to the ATT&CK framework's privilege escalation and defense evasion techniques, particularly concerning kernel-level manipulation of synchronization primitives. By properly implementing IRQ-safe locking mechanisms, the fix addresses potential attack vectors where adversaries might attempt to exploit lock contention scenarios in GPU driver subsystems. The solution represents a fundamental improvement in kernel security posture that aligns with industry standards for robust kernel module development practices and proper handling of shared kernel resources across different execution contexts.