CVE-2026-68455

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

liveupdate: validate session type before performing operation

The sessions ioctls are not applicable to all session types. PRESERVEFD is only applicable to outgoing sessions. RETRIEVEFD and FINISH are only valid for incoming session. Calling a incoming ioctl on an outgoing session is invalid and can cause file handlers to run into unexpected errors.

For example, a user can create a (outgoing) session, preserve a memfd, and then immediately do a retrieve without doing a kexec in between. This would result in memfd's retrieve handler to run. The handlers expects to be called from a post-kexec context, and will try to do a khorestorevmalloc() or khorestorefolio() to try and restore memory.

KHO catches this (thanks to KHOPAGEMAGIC) and returns an error, but since this is considered an internal error and KHO throws out a bunch of WARN()s.

Associate a type with each ioctl op and validate the type in luosessionioctl() before dispatching the ioctl handler to make sure the op is being called for the right session type.