CVE-2026-98209 in Linux
Summary
by MITRE • 10/06/2026
In the Linux kernel, the following vulnerability has been resolved:
mmc: sdhci-of-aspeed: Remove children before releasing SDC resources
Probe failure and removal leave SDHCI child devices registered after the parent clock and managed resources are released.
Unregister the OF children in reverse order before disabling the parent clock on both paths. Use of_platform_device_destroy() because manual child creation does not set the flag required by of_platform_depopulate().
This issue was identified during our ongoing static-analysis research while reviewing kernel code.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability described involves a resource management error within the Linux kernel's MultiMediaCard subsystem, specifically affecting the SDHCI driver for ASPEED SoCs. The core technical flaw lies in the incorrect ordering of operations during device probe failure and removal sequences. When an initialization fails or when the device is being removed, the parent clock and managed resources are released before the associated child devices registered via Open Firmware (OF) are properly unregistered. This sequence error results in a state where SDHCI child devices remain registered in the kernel's device model despite their underlying hardware resources having already been freed or disabled. Such an inconsistency creates a dangerous window for use-after-free conditions, as subsequent operations targeting these orphaned child devices may attempt to access memory or hardware registers that are no longer validly mapped or powered on by the system.
This issue was identified through static analysis research aimed at detecting kernel code defects related to resource lifecycle management. The root cause is a logical oversight in the driver's cleanup path where the dependency between parent clock control and child device registration is not strictly enforced during teardown. By failing to unregister OF children before disabling the parent clock, the system violates fundamental principles of hierarchical device tree handling. This can lead to kernel panics, data corruption, or unpredictable behavior if other subsystems attempt to interact with these stale device structures. The vulnerability highlights a common class of bugs in driver development where error paths are not as rigorously tested as success paths, leading to incomplete cleanup routines that leave the system state inconsistent and vulnerable to exploitation by local attackers who can trigger probe failures or device removal events.
From a security perspective, this flaw aligns with CWE-416, Use After Free, as it involves accessing resources after they have been effectively deallocated from the driver's perspective. It also relates to CWE-390, Detection of Error Condition Without Action, in cases where probe failures are handled but leave residual state that can be exploited later. In terms of MITRE ATT&CK mapping for Linux systems, this type of vulnerability could potentially facilitate privilege escalation if an attacker can trigger the specific conditions leading to the use-after-free scenario and exploit the resulting memory corruption to execute arbitrary code with kernel privileges. The impact is primarily on system stability and integrity, but in a multi-tenant or high-security environment, it represents a significant risk vector for local privilege escalation attacks targeting the Linux kernel surface.
To mitigate this vulnerability, the fix involves restructuring the removal logic within the sdhci-of-aspeed driver to ensure that OF children are unregistered in reverse order before the parent clock is disabled. This ensures that all references to child devices are cleared while their resources are still valid and accessible for proper cleanup. The implementation specifically utilizes of_platform_device_destroy() rather than relying solely on of_platform_depopulate(), as manual creation of child devices does not set the flags required by depopulate functions to handle destruction correctly. System administrators should ensure that kernel updates incorporating this fix are applied promptly, particularly in environments running ASPEED-based hardware where MMC/SD card interfaces are actively used. Regular auditing of driver code for proper resource ordering during error paths and removal sequences is recommended as a best practice to prevent similar issues across the broader Linux ecosystem.