[PATCH 3.5 40/78] USB: mos7840: fix tiocmget error handling

[Luis Henriques]

3.5.7.26 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <jhovold@xxxxxxxxx>

commit a91ccd26e75235d86248d018fe3779732bcafd8d upstream.

Make sure to return errors from tiocmget rather than rely on
uninitialised stack data.

Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 drivers/usb/serial/mos7840.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index d9368be..08aad01 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -1707,7 +1707,11 @@ static int mos7840_tiocmget(struct tty_struct *tty)
 		return -ENODEV;
 
 	status = mos7840_get_uart_reg(port, MODEM_STATUS_REGISTER, &msr);
+	if (status != 1)
+		return -EIO;
 	status = mos7840_get_uart_reg(port, MODEM_CONTROL_REGISTER, &mcr);
+	if (status != 1)
+		return -EIO;
 	result = ((mcr & MCR_DTR) ? TIOCM_DTR : 0)
 	    | ((mcr & MCR_RTS) ? TIOCM_RTS : 0)
 	    | ((mcr & MCR_LOOPBACK) ? TIOCM_LOOP : 0)
-- 
1.8.3.2

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