CVE-2026-23079: Linux Kernel GPIO Resource Leak Vulnerability

CVE-2026-23079 Overview

A resource leak vulnerability has been identified in the Linux kernel's GPIO character device subsystem. The vulnerability exists in the lineinfo_changed_notify() function, which fails to properly free allocated resources when encountering errors during execution. This improper error handling leads to memory leaks that can accumulate over time, potentially impacting system stability and resource availability.

Critical Impact

Memory leak in Linux kernel GPIO subsystem can lead to resource exhaustion and system instability on affected systems handling GPIO line information change notifications.

Affected Products

• Linux kernel (GPIO character device subsystem)
• Systems utilizing GPIO line information change notification functionality
• Embedded devices and servers with GPIO hardware interfaces

Discovery Timeline

• 2026-02-04 - CVE CVE-2026-23079 published to NVD
• 2026-02-05 - Last updated in NVD database

Technical Details for CVE-2026-23079

Vulnerability Analysis

This vulnerability represents a Memory Leak in the Linux kernel's GPIO character device driver. The lineinfo_changed_notify() function is responsible for notifying userspace applications when GPIO line information changes. During normal operation, this function allocates memory resources to handle the notification process.

The flaw occurs in the error handling paths within this function. When an error condition is encountered during the notification process, the function fails to release the previously allocated resources before returning. This results in orphaned memory allocations that cannot be reclaimed by the system.

Over time, repeated triggering of these error paths can lead to significant memory consumption, potentially resulting in system performance degradation or denial of service conditions. This is particularly concerning in embedded systems or long-running server environments where GPIO operations may be frequent.

Root Cause

The root cause of this vulnerability is improper error handling in the lineinfo_changed_notify() function within the GPIO character device driver code. When the function encounters an error condition after resource allocation, it returns immediately without first calling the appropriate cleanup routines to free the allocated memory. This programming oversight results in a memory leak that persists for the lifetime of the kernel.

Attack Vector

The attack vector for this vulnerability is currently classified as unknown. Exploitation would require the ability to trigger error conditions in the GPIO line information change notification pathway. This could potentially be achieved through:

• Repeated GPIO configuration operations that trigger error conditions
• Crafted userspace interactions with the GPIO character device interface
• Creating conditions that cause the notification mechanism to fail

While direct exploitation for code execution is unlikely, an attacker with local access could potentially leverage this vulnerability to exhaust system memory resources, leading to a denial of service condition.

The vulnerability has been addressed through kernel patches that ensure proper resource cleanup on all error paths within the affected function. Technical details of the fix can be found in the Linux Kernel Commit 16414341 and Linux Kernel Commit 70b3c28.

Detection Methods for CVE-2026-23079

Indicators of Compromise

• Gradual increase in kernel memory usage over time without corresponding system activity
• Unexplained memory pressure on systems with active GPIO operations
• Kernel memory allocation failures in environments with frequent GPIO line information changes
• System instability or out-of-memory conditions in embedded devices utilizing GPIO interfaces

Detection Strategies

• Monitor kernel memory allocation patterns using tools like /proc/meminfo and /proc/slabinfo
• Implement memory usage trending to detect gradual leaks associated with GPIO operations
• Review kernel logs for memory allocation failures or warnings related to GPIO subsystem
• Use kernel memory debugging tools such as KASAN or kmemleak to identify memory leak patterns

Monitoring Recommendations

• Configure system monitoring to alert on sustained memory growth in kernel space
• Implement periodic memory auditing on systems with high GPIO activity
• Deploy endpoint detection solutions capable of monitoring kernel-level resource consumption
• Establish baseline memory usage profiles for systems utilizing GPIO interfaces to detect anomalies

How to Mitigate CVE-2026-23079

Immediate Actions Required

• Update affected Linux kernel installations to patched versions containing the fix
• Monitor system memory usage for signs of resource exhaustion on systems with active GPIO operations
• Consider limiting GPIO character device access to trusted users and processes
• Plan maintenance windows for kernel updates on production systems

Patch Information

The Linux kernel development team has released patches to address this vulnerability. The fix ensures that all allocated resources are properly freed on error paths within the lineinfo_changed_notify() function.

Patches are available at:

• Linux Kernel Commit 16414341
• Linux Kernel Commit 70b3c28

System administrators should apply the appropriate kernel updates according to their distribution's security advisory processes.

Workarounds

• Restrict access to GPIO character device files (/dev/gpiochip*) to essential users and services only
• Implement periodic system reboots during maintenance windows to reclaim leaked memory on unpatched systems
• Monitor memory consumption and establish alerting thresholds to detect potential resource exhaustion
• Consider disabling GPIO character device functionality if not required for system operation

# Restrict GPIO device access (temporary mitigation)
chmod 600 /dev/gpiochip*
chown root:root /dev/gpiochip*

# Monitor kernel memory usage
watch -n 60 'cat /proc/meminfo | grep -E "MemFree|Slab|SUnreclaim"'