In the Linux kernel, the following vulnerability has been resolved: USB: serial: fix ioctl hangup race The tty ioctls can race with hangup and end up calling into a tty driver for a device that is already gone or powered down. Serialise the callbacks using the tty port mutex and add the missing checks to make sure the port has not been hung up before accessing port driver data or hardware. This specifically avoids dereferencing a NULL-pointer if a device is disconnected during lengthy break signalling. Note that TIOCGICOUNT and TIOCMIWAIT do not access port driver data or hardware and are therefore not affected by the race.
https://git.kernel.org/stable/c/ae0e61d95677efa778379853e495d748e6efbf95
https://git.kernel.org/stable/c/ae0da9a5c1ca95c20cc5feffd511ce6eae75924e
https://git.kernel.org/stable/c/7912a95d1345c77d8d63b530b00c118700b78abd
https://git.kernel.org/stable/c/4597ddd6168ae2a4123404e5f0871f1070dc7773