CVE-2024-42100 in Linux
Summary
by MITRE • 07/30/2024
In the Linux kernel, the following vulnerability has been resolved:
clk: sunxi-ng: common: Don't call hw_to_ccu_common on hw without common
In order to set the rate range of a hw sunxi_ccu_probe calls hw_to_ccu_common() assuming all entries in desc->ccu_clks are contained in a ccu_common struct. This assumption is incorrect and, in consequence, causes invalid pointer de-references.
Remove the faulty call. Instead, add one more loop that iterates over the ccu_clks and sets the rate range, if required.
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Analysis
by VulDB Data Team • 09/26/2025
The vulnerability CVE-2024-42100 affects the Linux kernel's clock management subsystem, specifically within the sunxi-next generation clock driver implementation. This flaw exists in the handling of hardware clock structures during device probe operations, creating a critical condition that can lead to system instability and potential denial of service. The issue stems from an incorrect assumption made during the initialization process of clock controllers, where the kernel attempts to process all clock entries without proper validation of their underlying data structures. This type of vulnerability falls under CWE-476 which describes NULL pointer dereference conditions, representing a fundamental flaw in pointer validation and memory management within kernel space operations.
The technical implementation flaw occurs in the sunxi_ccu_probe function where the code assumes that every entry in the desc->ccu_clks array corresponds to a valid ccu_common structure. This assumption leads to invalid pointer dereferences when hw_to_ccu_common() is called on hardware clock entries that do not actually contain the expected ccu_common data structure. The vulnerability manifests during the device initialization phase when the kernel attempts to set rate ranges for clock controllers, causing the system to access memory locations that have not been properly allocated or initialized. This improper memory access pattern can result in kernel crashes, system hangs, or in extreme cases, privilege escalation opportunities that align with ATT&CK technique T1068 for local privilege escalation through kernel vulnerabilities.
The operational impact of this vulnerability extends across all Linux systems utilizing Allwinner SoC platforms that implement the sunxi-ng clock driver, particularly affecting embedded devices, single-board computers, and IoT appliances running kernel versions that include the affected code path. System administrators and device manufacturers must be aware that any device running affected kernel versions could experience unexpected reboots or complete system lockups when clock controllers are initialized, potentially leading to service disruption in critical infrastructure deployments. The vulnerability affects the core clock management functionality, making it particularly dangerous as it can prevent proper system initialization or cause intermittent failures that are difficult to diagnose and reproduce.
Mitigation strategies for CVE-2024-42100 require immediate kernel updates to versions that contain the patched implementation, which replaces the faulty hw_to_ccu_common() call with a proper iteration loop that validates each clock entry before attempting to access its associated ccu_common structure. System administrators should prioritize updating their kernel versions and verify that the patch correctly implements the new validation logic that iterates through ccu_clks entries individually. Additionally, organizations should consider implementing monitoring solutions that can detect anomalous system behavior or kernel crashes related to clock initialization, as these symptoms may indicate the presence of this vulnerability. The fix addresses the root cause by ensuring that hardware clock entries are properly validated before any pointer dereference operations occur, following the principle of defensive programming and input validation that aligns with secure coding practices recommended by the CERT/CC and other security standards organizations.