tty: ttybuffer: Fix the softlockup issue in flushto_ldisc
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 v4.19.218 by commit 4f300f47dbcf9c3d4b2ea76c8554c8f360400725. For more details please see the references link.