The NSM driver's missing .owner assignment is a one-line omission, but the vulnerability it creates is a structural failure in how the misc subsystem handles the fops->owner contract. The misc_open() function uses fops_get() to pin registered file operations, assuming the owner pointer is valid — yet the subsystem never validates this field during device registration. When the module unloads, the file operations remain pinned but reference unmapped kernel text. A subsequent ioctl on the dangling fd dereferences a function pointer from freed memory, causing a controlled jump to a now-unmapped text section.
The exploitability of this pattern depends on three factors the CVE description doesn't address: the access control on /dev/nsm (whether unprivileged users can trigger it), whether the module can be forcibly unloaded, and whether specific ioctl handlers have side effects chainable into privilege escalation. Without knowing the device's permission model, you cannot assess actual risk.
What matters more than this individual driver is the systemic question: the fix is trivially copy-pasteable, which suggests either this was an isolated mistake or a common pattern the subsystem never audited for. Other registration paths in the kernel core were hardened around 2018-2019 when the dangling-fops use-after-free class became understood — misc appears to have fallen through that hardening wave precisely because it functions as the kernel's catch-all for drivers that don't fit elsewhere. The misc subsystem has no central maintainer pushing remediation; it depends on individual driver authors reading security lists and backporting fixes.
Your priority: check whether /dev/nsm requires CAP_SYS_ADMIN or is world-accessible. Then audit your misc drivers for NULL .owner assignments — the pattern is grep -r '.owner\s*=' in your misc driver tree. Assume the pattern is more widespread than this single CVE suggests, because the registration path was never hardened to reject it.