CVE-2023-52882 in Linux
Summary
by MITRE • 05/30/2024
In the Linux kernel, the following vulnerability has been resolved:
clk: sunxi-ng: h6: Reparent CPUX during PLL CPUX rate change
While PLL CPUX clock rate change when CPU is running from it works in vast majority of cases, now and then it causes instability. This leads to system crashes and other undefined behaviour. After a lot of testing (30+ hours) while also doing a lot of frequency switches, we can't observe any instability issues anymore when doing reparenting to stable clock like 24 MHz oscillator.
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Analysis
by VulDB Data Team • 04/07/2026
The vulnerability CVE-2023-52882 addresses a critical instability issue within the Linux kernel's clock management subsystem, specifically affecting the Allwinner H6 SoC architecture. This flaw manifests in the sunxi-ng clock driver implementation where the PLL CPUX clock rate change operation causes system instability when the CPU is operating from this clock source. The vulnerability represents a failure in clock domain management that can lead to system crashes and unpredictable behavior during frequency transitions. The issue affects embedded systems and devices utilizing Allwinner H6 processors, which are commonly found in single-board computers, embedded devices, and IoT applications where stable clock management is crucial for system reliability. The root cause lies in the timing and dependency management during PLL clock rate changes, where the system does not properly handle the transition when the CPU is directly utilizing the PLL CPUX clock source.
The technical flaw stems from the absence of proper clock reparenting during PLL CPUX rate changes, creating a scenario where the system attempts to modify the clock frequency while the CPU is actively running from that same clock source. This creates a race condition and timing dependency issue that manifests as system instability during frequency switching operations. When the CPU operates from the PLL CPUX clock and that clock rate is modified, the system experiences undefined behavior that can result in complete system crashes. The vulnerability is classified as a clock management failure that violates fundamental principles of embedded system design where clock domains must be carefully managed during frequency transitions. This issue directly relates to CWE-681, which addresses "Incorrect Use of a Constructor or Initializer" in the context of clock domain management, and also aligns with ATT&CK technique T1489 which covers system network configuration modification that can lead to system instability. The vulnerability demonstrates poor resource management and inadequate dependency handling in the kernel's clock subsystem.
The operational impact of CVE-2023-52882 extends beyond simple system crashes to encompass complete system unreliability in embedded environments where consistent performance is essential. Devices utilizing affected Allwinner H6 systems may experience random system failures during normal operation, particularly when dynamic frequency scaling is active or when system load causes clock rate adjustments. This instability can be particularly problematic in industrial applications, network infrastructure devices, or any system where uptime and predictable behavior are critical requirements. The vulnerability affects systems that rely on dynamic clock management for power optimization or performance scaling, making it particularly concerning for mobile devices, embedded systems, and IoT deployments. The intermittent nature of the instability makes this vulnerability difficult to detect during normal testing cycles, potentially allowing it to remain undetected in production environments until specific usage patterns trigger the instability. Systems running with the affected kernel versions may experience complete system hangs, kernel panics, or corrupted system states during normal operation, particularly under load conditions that require frequency switching.
The mitigation for CVE-2023-52882 involves implementing proper clock reparenting during PLL CPUX rate changes by temporarily switching the CPU clock source to a stable oscillator before modifying the PLL rate. This approach ensures that the CPU operates from a fixed, reliable clock source during the rate change operation, eliminating the race condition and timing dependencies that cause the instability. The fix implemented in the kernel ensures that when a PLL CPUX rate change is required, the system first reparents the CPU clock to a stable 24 MHz oscillator, performs the rate change operation, and then reparents back to the PLL CPUX source. This solution addresses the fundamental clock management issue by providing proper temporal separation between clock source changes and CPU operation, preventing the system from attempting to modify a clock source while actively using it. The mitigation aligns with industry best practices for embedded system design and follows established patterns for handling clock domain transitions in SoC architectures. Organizations should update their kernel versions to include this fix and should also implement monitoring for systems that may be affected by this vulnerability, particularly in environments where system stability is paramount. The solution effectively prevents the race condition and timing dependency that causes system instability while maintaining the intended functionality of dynamic frequency scaling.