A race condition was found in the GSM 0710 tty multiplexor in the Linux kernel. This issue occurs when two threads execute the GSMIOCSETCONF ioctl on the same tty file descriptor with the gsm line discipline enabled, and can lead to a use-after-free problem on a struct gsmdlci while restarting the gsm mux. This could allow a local unprivileged user to escalate their privileges on the system.