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.