From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 12 Oct 2009 17:13:54 +0000 (+0200)
Subject: tty, serial: Fix race and NULL check in uart_close()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=eea7e17e0eb23729d58368420659f8e7c357d82e;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

tty, serial: Fix race and NULL check in uart_close()

Commit 46d57a449aa1 ("serial: use tty_port pointers in the core code")
contained two bugs that causes (rare) crashes:

 - the rename typoed one site

 - a NULL check was missed

Reported-and-tested-by: Ingo Molnar <mingo@elte.hu>
Cc: Greg KH <gregkh@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 1689bda1d13b..dcc72444e8e7 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1270,6 +1270,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 
 	BUG_ON(!kernel_locked());
 
+	if (!state)
+		return;
+
 	uport = state->uart_port;
 	port = &state->port;
 
@@ -1316,9 +1319,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 	 */
 	if (port->flags & ASYNC_INITIALIZED) {
 		unsigned long flags;
-		spin_lock_irqsave(&port->lock, flags);
+		spin_lock_irqsave(&uport->lock, flags);
 		uport->ops->stop_rx(uport);
-		spin_unlock_irqrestore(&port->lock, flags);
+		spin_unlock_irqrestore(&uport->lock, flags);
 		/*
 		 * Before we drop DTR, make sure the UART transmitter
 		 * has completely drained; this is especially