linux-kernel - [PATCH 4.9 11/32] USB: serial: ch341: fix type promotion bug in ch341_control

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Date:   Mon, 16 Jul 2018 09:36:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Johan Hovold <johan@...nel.org>
Subject: [PATCH 4.9 11/32] USB: serial: ch341: fix type promotion bug in ch341_control_in()

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

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

From: Dan Carpenter <dan.carpenter@...cle.com>

commit e33eab9ded328ccc14308afa51b5be7cbe78d30b upstream.

The "r" variable is an int and "bufsize" is an unsigned int so the
comparison is type promoted to unsigned.  If usb_control_msg() returns a
negative that is treated as a high positive value and the error handling
doesn't work.

Fixes: 2d5a9c72d0c4 ("USB: serial: ch341: fix control-message error handling")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Cc: stable <stable@...r.kernel.org>
Signed-off-by: Johan Hovold <johan@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/serial/ch341.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -118,7 +118,7 @@ static int ch341_control_in(struct usb_d
 	r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 			    USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 			    value, index, buf, bufsize, DEFAULT_TIMEOUT);
-	if (r < bufsize) {
+	if (r < (int)bufsize) {
 		if (r >= 0) {
 			dev_err(&dev->dev,
 				"short control message received (%d < %u)\n",