CVE-2026-90158: m68k: nfcon: Do not call console_is_registered() in nfcon_device()
In the Linux kernel, the following vulnerability has been resolved:
m68k: nfcon: Do not call consoleisregistered() in nfcondevice()
Since 7c2af0f634f1 ("tty: ttyio: use consolelistlock for list synchronization") showconsactive() calls the .device() method under the consolelistlock, but consoleisregistered() tries to acquire consolelistlock as well, causing a deadlock. It should not be necessary to check consoleisregistered() here since the function should not be called in the fist place when the console is not registered.
Event History
Frequently Asked Questions
What conditions are required to trigger the deadlock?
The issue occurs when show_cons_active() invokes the nfcon console .device() method while holding console_list_lock. nfcon_device() then calls console_is_registered(), which attempts to acquire the same lock again.
What systems are exposed to this issue?
The affected code is in the Linux kernel's m68k nfcon console support. The description does not identify affected distributions, kernel versions, or configurations beyond use of this console path.
Is there a workaround if the fix cannot be applied immediately?
The provided data does not describe a workaround. The resolved change removes the console_is_registered() call from nfcon_device(), because the device method should not be called for an unregistered console.