CVE-2025-21982 in Linux
Summary
by MITRE • 04/01/2025
In the Linux kernel, the following vulnerability has been resolved:
pinctrl: nuvoton: npcm8xx: Add NULL check in npcm8xx_gpio_fw
devm_kasprintf() calls can return null pointers on failure. But the return values were not checked in npcm8xx_gpio_fw(). Add NULL check in npcm8xx_gpio_fw(), to handle kernel NULL pointer dereference error.
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Analysis
by VulDB Data Team • 02/01/2026
The vulnerability identified as CVE-2025-21982 affects the Linux kernel's pinctrl subsystem, specifically within the Nuvoton NPCM8xx GPIO driver implementation. This issue resides in the npcm8xx_gpio_fw function where improper handling of devm_kasprintf() return values creates a potential null pointer dereference condition. The vulnerability represents a classic software error pattern that can lead to system instability and potential security implications within embedded systems utilizing Nuvoton NPCM8xx SoCs. The affected driver is responsible for managing GPIO (General Purpose Input/Output) functionality in these embedded processors, making it a critical component for system operation and security.
The technical flaw manifests when devm_kasprintf() function fails to allocate memory for string formatting operations, returning a null pointer instead of the expected formatted string. This function is commonly used in kernel space for dynamic string construction and memory management. The npcm8xx_gpio_fw() function fails to validate the return value from devm_kasprintf() before proceeding with subsequent operations that assume a valid pointer. This oversight creates a direct path for null pointer dereference errors when the code attempts to use the null return value as if it were a valid memory reference. According to CWE-476, this vulnerability maps directly to a null pointer dereference condition where the code does not properly handle cases where memory allocation functions fail.
The operational impact of this vulnerability extends beyond simple system crashes or hangs. In embedded systems utilizing Nuvoton NPCM8xx processors, such as industrial control systems, network appliances, or automotive applications, a null pointer dereference can lead to complete system failure or unpredictable behavior. The vulnerability affects the GPIO subsystem which is fundamental to system boot processes, device initialization, and hardware interface management. When triggered, this condition can cause kernel oops, system panics, or more subtle operational failures that might persist undetected. The attack surface is particularly concerning in environments where system reliability is paramount, as this could potentially be exploited to cause denial of service or create conditions for further attacks.
Mitigation strategies for CVE-2025-21982 involve implementing proper null pointer validation in the npcm8xx_gpio_fw() function. The recommended approach requires adding explicit checks for devm_kasprintf() return values before any subsequent operations that might use the returned pointer. This aligns with the ATT&CK framework's defensive techniques for preventing kernel-level vulnerabilities, specifically addressing the T1547.006 technique related to kernel rootkits and T1068 technique for local privilege escalation through kernel exploitation. System administrators should ensure kernel updates are applied promptly, as this vulnerability affects the core kernel functionality rather than user-space applications. Additionally, monitoring systems should be configured to detect kernel oops or system panics that might indicate exploitation attempts, particularly in environments where these embedded systems are deployed. The fix should be implemented as a defensive programming practice that validates all memory allocation results, following the principle of least privilege and secure coding standards recommended by organizations such as the Open Web Application Security Project and the CERT Coordination Center.