From: Johan Hovold <johan@kernel.org>
Date: Thu, 12 Jan 2017 13:56:17 +0000 (+0100)
Subject: USB: serial: mos7720: fix control-message error handling
X-Git-Tag: v3.18.74~23
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=920027fef71971daf64658c6f6bbfdebde161b0a;p=thirdparty%2Fkernel%2Fstable.git

USB: serial: mos7720: fix control-message error handling


[ Upstream commit 0d130367abf582e7cbf60075c2a7ab53817b1d14 ]

Make sure to log an error on short transfers when reading a device
register.

Also clear the provided buffer (which if often an uninitialised
automatic variable) on errors as the driver currently does not bother to
check for errors.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index c3b8ae3604247..5e3a609fbab4f 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -236,11 +236,16 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
 
 	status = usb_control_msg(usbdev, pipe, request, requesttype, value,
 				     index, buf, 1, MOS_WDR_TIMEOUT);
-	if (status == 1)
+	if (status == 1) {
 		*data = *buf;
-	else if (status < 0)
+	} else {
 		dev_err(&usbdev->dev,
 			"mos7720: usb_control_msg() failed: %d\n", status);
+		if (status >= 0)
+			status = -EIO;
+		*data = 0;
+	}
+
 	kfree(buf);
 
 	return status;