CVE-2026-68180 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
intel_th: fix MSC output device reference leak
intel_th_output_open() looks up the output device with bus_find_device_by_devt(), which returns the device with a reference that must be dropped after use.
commit 95fc36a234da ("intel_th: fix device leak on output open()") attempted to drop the reference from intel_th_output_release(). However, a successful open replaces file->f_op with the output driver file operations before returning, so close runs the output driver release callback instead.
For MSC outputs, close runs intel_th_msc_release(), which only removes the per-file iterator and does not drop the device reference taken by intel_th_output_open(). Consequently, every successful MSC output open leaks one device reference.
Drop the device reference from intel_th_msc_release(), which is the release path actually used for MSC output files. Remove the now-unused intel_th_output_release() callback from intel_th_output_fops.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability in question affects the Intel Trace Hub subsystem within the Linux kernel, specifically targeting the management of device references during MSC (Multi-Stream Counter) output operations. This issue stems from improper reference counting mechanisms that lead to resource leakage within the kernel's device management framework. The problem manifests when the intel_th_output_open() function performs a lookup operation using bus_find_device_by_devt() which returns a device with an acquired reference that must be explicitly released after use. The original attempt to address this through commit 95fc36a234da introduced a flawed approach by attempting to drop references from the intel_th_output_release() callback, but this solution fails due to the operational flow of the system.
The core technical flaw occurs because successful device opening operations replace the file's operation structure (file->f_op) with output driver file operations before returning control to the caller. When a close operation subsequently occurs, it executes the output driver release callback rather than the original one that was intended to handle reference cleanup. For MSC output devices specifically, the intel_th_msc_release() function handles the close operation but only removes per-file iterators without dropping the device reference that was acquired during the open phase by intel_th_output_open(). This creates a persistent reference leak where each successful MSC output open operation results in one unreleased device reference, gradually consuming kernel memory resources over time.
The operational impact of this vulnerability extends beyond simple resource exhaustion, potentially affecting system stability and performance degradation as reference leaks accumulate. The issue represents a classic case of improper resource management where the kernel's device reference counting mechanism fails to properly account for all references acquired during device operations. This type of vulnerability falls under CWE-404, which specifically addresses resource leaks in software systems, and aligns with ATT&CK technique T1547.001 related to registry run keys and startup folder modifications that could be exploited through compromised kernel components. The leak occurs at the kernel level where device references are not properly managed during the device lifecycle, creating a persistent state where the kernel cannot properly reclaim memory associated with these device objects.
The mitigation strategy involves modifying the intel_th_msc_release() function to properly drop the device reference that was acquired during the open operation, ensuring that all acquired references are accounted for in the release path. Additionally, the unused intel_th_output_release() callback is removed from intel_th_output_fops since it is no longer needed and could potentially introduce further confusion in the codebase. This fix ensures proper reference counting throughout the device lifecycle by guaranteeing that every reference acquired during open operations is properly released during corresponding close operations. The solution maintains the existing functionality while addressing the fundamental resource management issue, aligning with kernel security best practices for preventing memory leaks and maintaining system stability under sustained usage conditions.