CVE-2023-53805 tty: n_gsm: fix UAF in gsm_cleanup_mux

In the Linux kernel, the following vulnerability has been resolved: tty: ngsm: fix UAF in gsmcleanupmux In gsmcleanupmux the 'gsm-dlci' pointer was not cleaned properly, leaving it a dangling pointer after gsmdlcirelease. This leads to use-after-free where 'gsm-dlci0' are freed and accessed by th...