staging: greybus: uart: fix tty use after free
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 v4.14.249 by commit 64062fcaca8872f063ec9da011e7bf30470be33f, it was introduced in version v4.9 by commit a18e15175708d39abbe9746ddc3479466b7800c3. For more details please see the references link.