From 2e758910832dce99761a29688b33fd77dcbf6f6c Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Thu, 16 Oct 2014 16:54:19 -0400 Subject: [PATCH] serial: core: Flush ldisc after dropping port mutex in uart_close() The tty buffers (and any line discipline buffers) must be flushed after the UART hardware has shutdown; otherwise, a racing open on the same tty may receive data from the previous session, which is a security hazard. However, holding the port mutex while flushing the line discipline buffers creates a lock inversion if the set_termios() handler takes the port mutex (as it does in the followup patch, 'serial: Fix locking for uart driver set_termios method'. Flush the ldisc buffers after dropping the port mutex; the tty lock is still held which prevents a concurrent open() from advancing while flushing. Since no new rx data is possible after uart_shutdown() until a new open reinitializes the port, the later flush has no impact on what data is being discarded. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- Reading git-format-patch failed