The Linux kernel vulnerability CVE-2026-64021 involves a reference leak in the drm/xe driver's exec_queue during the xe_oa_stream_open_ioctl() function. When the exec_queue width parameter exceeded 1, the function returned -EOPNOTSUPP prematurely, bypassing the cleanup code that releases the exec_queue reference obtained via xe_exec_queue_lookup(). Because the leaked reference is not part of the file's exec_queue xarray, it cannot be released on file close, resulting in indefinite retention of the exec_queue and file private state. The fix changes the code to jump to the error cleanup path instead of returning directly, ensuring proper release of the reference.

The vulnerability causes a resource leak in the Linux kernel's drm/xe driver, which can lead to indefinite retention of kernel objects related to exec_queue and file private state. This may result in increased memory usage and potential denial of service due to resource exhaustion. There is no indication of code execution or privilege escalation from the provided data.

A fix has been applied to the Linux kernel source code to address this issue by correcting the error handling path to release the leaked reference. Users should update their Linux kernel to a version that includes this fix. Patch status is not explicitly stated; check the vendor or Linux kernel advisories for the exact fixed versions and apply updates accordingly.