CVE-2026-90215

In the Linux kernel, the following vulnerability has been resolved:

mtd: ubi: Release device reference on busy detach

ubi_detach_mtd_dev() obtains a device reference through ubi_get_device()
before checking whether the UBI device is busy. The busy return path drops
ubi->ref_count but leaves the device reference held, so the device object
cannot be released after a later detach.

Drop the device reference before returning -EBUSY.