CVE-2026-89522
Summary
by MITRE • 09/11/2026
In the Linux kernel, the following vulnerability has been resolved:
media: staging/ipu7: fix async notifier UAF on probe error path
isys_register_devices() registers the V4L2 async notifier via isys_notifier_init(). If a subsequent probe step such as isys_fw_log_init() fails, isys_probe() jumps to the out_cleanup label which only calls isys_unregister_devices(). That helper tears down the video devices, subdevices, V4L2 device and media device, but never unregisters or cleans up the async notifier.
As a result the notifier stays chained in the global notifier_list while the enclosing struct ipu7_isys is freed by devres, leading to list corruption and a use-after-free the next time the list is walked.
The remove path already does the right thing by calling isys_notifier_cleanup() before isys_unregister_devices(). Mirror that on the probe error path so the notifier is unregistered and cleaned up before the device is torn down.
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Analysis
by VulDB Data Team • 09/12/2026
This vulnerability represents a critical resource management flaw within the Linux kernel's media subsystem, specifically affecting the Intel IPU7 driver located in the staging directory. The core issue stems from an inconsistent implementation of error handling during the device probe phase compared to the removal path. When the isys_register_devices function initializes and registers the V4L2 async notifier via isys_notifier_init, it establishes a linkage within the global kernel notifier list. However, if any subsequent initialization step in the probe sequence fails, such as the failure of isys_fw_log_init, the execution flow diverts to an error handling label labeled out_cleanup. This specific cleanup routine invokes isys_unregister_devices, which systematically tears down video devices, subdevices, V4L2 devices, and media devices. Crucially, this function omits the necessary call to unregister or clean up the async notifier that was established earlier in the process.
The operational consequence of this omission is a severe use-after-free condition coupled with list corruption. Because the async notifier remains chained within the global notifier_list while its parent structure, struct ipu7_isys, is subsequently freed by device resource management mechanisms like devres, the kernel retains references to memory that has been deallocated. Any subsequent iteration or walk through the global notifier list will attempt to access this invalid memory address, leading to undefined behavior. This can manifest as system crashes, data corruption, or potential privilege escalation if an attacker can trigger the probe failure and manipulate the timing of list walks. The vulnerability is classified under CWE-416, Use After Free, which describes situations where a program uses a pointer that points to memory that has already been freed, often leading to unpredictable behavior and security breaches.
From a threat modeling perspective aligned with MITRE ATT&CK techniques, this flaw facilitates exploitation vectors related to Denial of Service via crash or instability (T1499) and potentially Memory Corruption (T1203). The lack of proper cleanup allows an attacker who can influence the probe process, perhaps through physical access or specific hardware states that trigger initialization failures, to destabilize the kernel. The asymmetry between the remove path and the probe error path is a common source of such bugs in driver development. While the removal function correctly calls isys_notifier_cleanup before unregistering devices, ensuring all references are severed prior to memory release, the probe error path fails to mirror this logic. This inconsistency creates a window where dangling pointers persist in global data structures even after the owning object has been destroyed.
To mitigate this vulnerability and restore robustness to the driver, it is imperative that the probe error handling path be updated to explicitly unregister and clean up the async notifier before proceeding with other device teardown operations. Specifically, the code must invoke isys_notifier_cleanup prior to calling isys_unregister_devices when an error occurs during probing. This ensures that the notifier is removed from the global list while its associated memory structures are still valid and accessible for proper cleanup. By aligning the probe error path logic with the established correct behavior of the remove path, developers can eliminate the use-after-free condition and prevent list corruption. Regular static analysis and code reviews focusing on resource acquisition and release symmetry in kernel drivers are recommended to detect such discrepancies early in the development lifecycle.