CVE-2025-40059 in Linux
Summary
by MITRE • 10/28/2025
In the Linux kernel, the following vulnerability has been resolved:
coresight: Fix incorrect handling for return value of devm_kzalloc
The return value of devm_kzalloc could be an null pointer, use "!desc.pdata" to fix incorrect handling return value of devm_kzalloc.
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Analysis
by VulDB Data Team • 05/20/2026
The vulnerability CVE-2025-40059 represents a critical null pointer dereference issue within the Linux kernel's CoreSight subsystem, which is responsible for debugging and tracing capabilities in embedded systems and ARM-based architectures. This flaw exists in the device management memory allocation functions where the devm_kzalloc() function is employed to allocate memory for CoreSight device descriptors. The issue arises from improper handling of the return value from this memory allocation function, which can legitimately return a NULL pointer when memory allocation fails. The vulnerability specifically affects systems utilizing CoreSight tracing infrastructure where device initialization routines do not properly validate the allocation result before proceeding with subsequent operations. This represents a classic software defect pattern that aligns with CWE-476, which describes null pointer dereference conditions in software systems. The improper validation creates a scenario where the kernel may attempt to access memory at a NULL address, leading to system crashes or potentially exploitable conditions that could allow privilege escalation or denial of service attacks.
The technical implementation of this vulnerability stems from the device management framework within the Linux kernel where devm_kzalloc() is used to allocate memory for CoreSight device data structures. When this allocation function fails, it returns NULL instead of a valid memory address, but the existing code does not check for this condition before using the returned pointer. The fix implemented addresses this by introducing a proper validation check using the "!desc.pdata" condition, which ensures that the code only proceeds with operations when valid memory has been successfully allocated. This approach follows established kernel development practices for memory management and aligns with the ATT&CK technique T1068, which covers privilege escalation through kernel vulnerabilities. The CoreSight subsystem is particularly critical in embedded systems where debugging and tracing capabilities are essential for system diagnostics and development, making this vulnerability particularly concerning for devices that rely heavily on these tracing features.
The operational impact of CVE-2025-40059 extends across various Linux kernel versions that incorporate the affected CoreSight driver code, particularly affecting ARM-based systems and embedded devices that utilize the Linux kernel for their operation. Systems running with CoreSight tracing enabled are vulnerable to potential system instability, where kernel crashes may occur during device initialization or when tracing operations are attempted. The vulnerability's exploitation potential depends on the specific context in which the affected code executes, but it could potentially be leveraged by malicious actors to cause system denial of service or to gain elevated privileges within the kernel space. The security implications are significant for embedded systems, IoT devices, and mobile platforms that rely on ARM architecture and CoreSight debugging capabilities. Organizations deploying Linux-based systems in critical infrastructure, automotive applications, or industrial control systems must consider this vulnerability as part of their security posture, particularly given the widespread use of CoreSight tracing in these environments. The fix implemented addresses the immediate memory management issue but also serves as a reminder of the importance of proper error handling in kernel code, which is fundamental to maintaining system stability and security in operating system implementations.