CVE-2026-68314 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
net: mctp i3c: clean up notifier and buses if driver register fails
mctp_i3c_mod_init() registers the I3C bus notifier and then walks the existing buses with i3c_for_each_bus_locked(mctp_i3c_bus_add_new, NULL) before registering the I3C device driver. If i3c_driver_register() fails, the function returns the error directly, leaving the notifier registered and every mctp_i3c_bus object created for the existing buses allocated. The notifier is left pointing into the module that failed to load and the bus list is leaked.
Mirror the module exit path on this failure: unregister the notifier and tear down the buses that were added before returning the error.
This issue was identified during our ongoing static-analysis research while reviewing kernel code.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability resides in the Linux kernel's MCTP (Management Component Transport Protocol) I3C driver implementation where a critical resource management flaw exists during driver initialization. This issue manifests when the mctp_i3c_mod_init() function attempts to register the I3C bus notifier and subsequently processes existing buses before registering the device driver itself. The fundamental problem occurs when i3c_driver_register() fails, causing the function to return the error immediately without properly cleaning up previously allocated resources. This creates a state where the I3C bus notifier remains registered but points to a module that failed to load correctly, while all mctp_i3c_bus objects created for existing buses remain allocated in memory. The vulnerability represents a classic resource leak scenario that can lead to system instability and potential denial of service conditions.
The technical flaw stems from inadequate error handling in the driver initialization sequence, specifically violating proper resource management principles where cleanup operations should occur regardless of whether initialization succeeds or fails. According to CWE-459, this constitutes a "Incomplete Cleanup" vulnerability where resources are not properly released when an operation fails. The flaw demonstrates poor defensive programming practices where the code path does not mirror the cleanup behavior that occurs during normal module exit procedures. When i3c_driver_register() returns an error, the function should execute the same cleanup operations that occur in the module exit path to ensure consistent resource management and prevent memory leaks.
The operational impact of this vulnerability extends beyond simple memory consumption as it can create persistent system instability and potentially provide attackers with opportunities for denial of service attacks. The leaked mctp_i3c_bus objects consume kernel memory that cannot be reclaimed until system reboot, while the dangling notifier reference creates a potential attack surface where malicious code could exploit the invalid pointer references. This vulnerability aligns with ATT&CK technique T1499.004 which involves resource exhaustion through improper cleanup of system resources. The issue becomes particularly concerning in embedded systems or environments where memory is constrained, as repeated failed driver registrations could lead to gradual system degradation and eventual crashes.
The recommended mitigation strategy involves implementing proper error handling that mirrors the module exit path during initialization failures. This requires modifying mctp_i3c_mod_init() to ensure that when i3c_driver_register() fails, the function unregisters the previously registered I3C bus notifier and tears down all bus objects created for existing buses before returning the error code. The fix should follow established kernel programming practices by implementing a consistent resource management pattern where every allocated resource has a corresponding cleanup operation. This approach ensures that the driver initialization sequence maintains the same cleanup semantics whether it succeeds or fails, preventing resource leaks and maintaining system stability. The solution directly addresses the root cause by ensuring that the error path properly cleans up all resources allocated during the successful portion of the initialization sequence.
The vulnerability highlights the importance of defensive programming in kernel space where resource management becomes critical due to the absence of garbage collection and the permanent nature of system resources. This type of issue commonly arises in complex driver frameworks where multiple subsystems must be initialized in a specific order, and failure at any point requires complete rollback of all previously successful operations. The static analysis approach used to identify this vulnerability demonstrates the value of automated code review tools in detecting subtle resource management issues that might otherwise go unnoticed until they manifest as system stability problems in production environments.