net/x25: Fix null-ptr-deref caused by x25_disconnect
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v4.9.311 by commit dffc859d1d9560da594e4282091781b8d2715f00, it was introduced in version v4.9.233 by commit 08560e93a2c1c93eefe166015f2351196fbbc8e1. For more details please see the references link.