CVE-2026-80655 in Linux
Summary
by MITRE • 08/28/2026
In the Linux kernel, the following vulnerability has been resolved:
soc: xilinx: Fix race condition in event registration
The zynqmp_power driver registers handlers for suspend and subsystem restart events using register_event(). However, the work structures (zynqmp_pm_init_suspend_work and zynqmp_pm_init_restart_work) used by these handlers were allocated and initialized after the registration call.
This created a race window where, if the firmware triggered an event immediately after registration but before allocation, the callback (suspend_event_callback or subsystem_restart_event_callback) would dereference a NULL pointer in work_pending(), leading to a crash.
Fix this by allocating and initializing the work structures before registering the events.
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Analysis
by VulDB Data Team • 08/28/2026
The Linux kernel driver for Xilinx ZynqMP power management contains a critical race condition within its event registration logic that can lead to system instability or denial of service. This vulnerability stems from an incorrect initialization sequence in the zynqmp_power driver, specifically regarding how handlers for suspend and subsystem restart events are registered with the kernel's workqueue infrastructure. The root cause lies in the temporal ordering of memory allocation versus function invocation during the driver probe phase. When the driver initializes, it calls register_event to bind specific callback functions, namely suspend_event_callback or subsystem_restart_event_callback, to system-wide power management notifications. However, at the moment these registration calls are executed, the underlying work structures required for asynchronous execution—specifically zynqmp_pm_init_suspend_work and zynqmp_pm_init_restart_work—are not yet allocated in memory nor initialized with their respective task functions.
This sequencing error creates a narrow but exploitable race window between the successful return of register_event and the subsequent allocation and initialization of the work structures. If the firmware triggers one of these power management events immediately after registration, before the driver has completed its setup routine to allocate the necessary memory for the work items, the kernel's event handling mechanism will attempt to schedule or execute the callback using uninitialized pointers. Specifically, when the system attempts to process the pending work item via work_pending(), it dereferences a NULL pointer because the expected data structure does not exist in memory at that address. This null pointer dereference results in an immediate kernel panic or crash, effectively causing a denial of service for the affected device. The vulnerability is particularly dangerous because firmware events can be triggered by external hardware states or power transitions that are outside the direct control of the operating system driver code, making it difficult to predict when the race condition might manifest during normal operation or boot sequences.
From a technical classification perspective, this flaw aligns with CWE-362, which describes concurrent execution using shared resources with improper synchronization, specifically manifesting here as a use-after-free or null pointer dereference due to uninitialized data access in a multi-threaded context. The attack vector is primarily local and requires physical or firmware-level interaction to trigger the specific timing window that leads to the crash, rather than remote network exploitation. In terms of the MITRE ATT&CK framework for enterprise security, this vulnerability relates to techniques involving resource manipulation during initialization phases, potentially allowing an attacker with access to system power management controls or compromised firmware to disrupt service availability by inducing a kernel panic through precise timing of event triggers.
To mitigate this vulnerability and prevent similar issues in future driver development, the primary remediation is strictly enforcing correct initialization order within device drivers. Developers must ensure that all data structures required for callback execution are fully allocated, initialized, and validated before any registration functions that might invoke those callbacks are called. In the specific case of the zynqmp_power driver, this involves moving the allocation and setup of zynqmp_pm_init_suspend_work and zynqmp_pm_init_restart_work to precede the register_event calls. Additionally, implementing defensive programming practices such as null pointer checks within callback functions can provide a secondary layer of defense against race conditions that may arise from complex asynchronous event handling in kernel space. System administrators should apply available kernel patches or updates provided by their distribution vendors to resolve this issue and restore system stability on affected Xilinx ZynqMP-based platforms.