CVE-2026-46258 in Linux
Summary
by MITRE • 06/03/2026
In the Linux kernel, the following vulnerability has been resolved:
gpio: cdev: Avoid NULL dereference in linehandle_create()
In linehandle_create(), there is a statement like this: retain_and_null_ptr(lh);
Soon after, there is a debug printout that dereferences "lh", which will crash things.
Avoid the crash by using handlereq.lines, which is the same value.
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Analysis
by VulDB Data Team • 06/05/2026
The vulnerability identified in the Linux kernel's gpio subsystem represents a critical null pointer dereference flaw that could lead to system instability and potential denial of service conditions. This issue specifically affects the cdev implementation within the gpio subsystem where the linehandle_create() function contains a logical error in its pointer management. The flaw manifests when the retain_and_null_ptr(lh) operation is executed followed immediately by a debug printout that attempts to dereference the lh pointer, creating a scenario where the system crashes upon encountering a NULL value that was previously assigned to the pointer variable. This type of vulnerability falls under the CWE-476 category of NULL Pointer Dereference, which is classified as a common weakness in software development practices that can lead to system crashes and potential exploitation by malicious actors.
The technical implementation of this vulnerability stems from improper pointer handling within the gpio character device driver where the retain_and_null_ptr() function is designed to transfer ownership of a pointer reference while simultaneously setting the original pointer to NULL. However, the subsequent debug printout operation in the same function does not account for this pointer nullification, creating a scenario where the debug code attempts to access memory through a NULL reference. This flaw demonstrates poor defensive programming practices and highlights the importance of proper resource management in kernel space operations where memory safety is paramount. The vulnerability is particularly concerning because it occurs in the gpio subsystem which is fundamental to hardware device communication and system functionality.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise the stability of embedded systems and server environments that rely heavily on gpio functionality for hardware interaction. When triggered, the null pointer dereference can cause immediate system termination or reboot cycles, disrupting critical hardware operations that depend on gpio lines for communication with peripheral devices. The vulnerability affects systems using the gpio character device interface where applications create line handles to interact with gpio pins, making it relevant to a wide range of embedded Linux systems including IoT devices, industrial control systems, and server hardware platforms. This type of kernel-level vulnerability also provides potential attack vectors for privilege escalation or system compromise, as attackers could exploit the crash conditions to disrupt services or potentially gain unauthorized access to system resources.
Mitigation strategies for this vulnerability require immediate kernel updates from vendors to address the specific pointer management issue in the linehandle_create() function. System administrators should prioritize patching affected kernel versions to prevent exploitation, particularly in environments where gpio functionality is critical for hardware operations. The fix involves modifying the debug printout code to reference handlereq.lines instead of the potentially null lh pointer, ensuring that the same value is accessed without risking null pointer dereference. Organizations should implement monitoring systems to detect unusual system crashes or reboot patterns that might indicate exploitation attempts, and consider implementing kernel hardening measures such as stack canaries and address space layout randomization to complicate potential exploitation attempts. Additionally, security teams should review gpio-related code implementations across their infrastructure to identify similar pointer management issues that might exist in custom or third-party kernel modules, ensuring comprehensive protection against similar vulnerabilities that could be leveraged through the attack surface defined by the ATT&CK framework's system binary modifications and privilege escalation techniques.