[RFT 9/9] Char: moxa, fix ioctl race

[Jiri Slaby <jirislaby@gmail.com>]

The lock fixes window between board->ready test and its port access.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
---
 drivers/char/moxa.c |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index fd9c946..6e170a4 100644
--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -299,6 +299,7 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
 		struct moxa_port *p;
 		unsigned int i, j;
 
+		mutex_lock(&moxa_openlock);
 		for (i = 0; i < MAX_BOARDS; i++) {
 			p = moxa_boards[i].ports;
 			for (j = 0; j < MAX_PORTS_PER_BOARD; j++, p++, argm++) {
@@ -307,10 +308,13 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
 					tmp.inq = MoxaPortRxQueue(p);
 					tmp.outq = MoxaPortTxQueue(p);
 				}
-				if (copy_to_user(argm, &tmp, sizeof(tmp)))
+				if (copy_to_user(argm, &tmp, sizeof(tmp))) {
+					mutex_unlock(&moxa_openlock);
 					return -EFAULT;
+				}
 			}
 		}
+		mutex_unlock(&moxa_openlock);
 		return 0;
 	} case MOXA_GET_OQUEUE:
 		status = MoxaPortTxQueue(ch);
@@ -324,6 +328,7 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
 		struct moxa_port *p;
 		unsigned int i, j;
 
+		mutex_lock(&moxa_openlock);
 		for (i = 0; i < MAX_BOARDS; i++) {
 			p = moxa_boards[i].ports;
 			for (j = 0; j < MAX_PORTS_PER_BOARD; j++, p++, argm++) {
@@ -344,10 +349,13 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
 				else
 					tmp.cflag = p->tty->termios->c_cflag;
 copy:
-				if (copy_to_user(argm, &tmp, sizeof(tmp)))
+				if (copy_to_user(argm, &tmp, sizeof(tmp))) {
+					mutex_unlock(&moxa_openlock);
 					return -EFAULT;
+				}
 			}
 		}
+		mutex_unlock(&moxa_openlock);
 		return 0;
 	}
 	case TIOCGSERIAL:
-- 
1.5.3.8