CVE-2026-31749

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

comedi: ni_atmio16d: Fix invalid clean-up after failed attach

If the driver's COMEDI "attach" handler function (`atmio16d_attach()`)

returns an error, the COMEDI core will call the driver's "detach"

handler function (`atmio16d_detach()`) to clean up. This calls

`reset_atmio16d()` unconditionally, but depending on where the error

occurred in the attach handler, the device may not have been

sufficiently initialized to call `reset_atmio16d()`. It uses

`dev->iobase` as the I/O port base address and `dev->private` as the

pointer to the COMEDI device's private data structure. `dev->iobase`

may still be set to its initial value of 0, which would result in

undesired writes to low I/O port addresses. `dev->private` may still be

`NULL`, which would result in null pointer dereferences.

Fix `atmio16d_detach()` by checking that `dev->private` is valid

(non-null) before calling `reset_atmio16d()`. This implies that

`dev->iobase` was set correctly since that is set up before

`dev->private`.