Patch "USB: serial: ch341: fix control-message error handling" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    USB: serial: ch341: fix control-message error handling

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-serial-ch341-fix-control-message-error-handling.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 2d5a9c72d0c4ac73cf97f4b7814ed6c44b1e49ae Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Fri, 6 Jan 2017 19:15:18 +0100
Subject: USB: serial: ch341: fix control-message error handling

From: Johan Hovold <johan@kernel.org>

commit 2d5a9c72d0c4ac73cf97f4b7814ed6c44b1e49ae upstream.

A short control transfer would currently fail to be detected, something
which could lead to stale buffer data being used as valid input.

Check for short transfers, and make sure to log any transfer errors.

Note that this also avoids leaking heap data to user space (TIOCMGET)
and the remote device (break control).

Fixes: 6ce76104781a ("USB: Driver for CH341 USB-serial adaptor")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/serial/ch341.c |   32 +++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -99,6 +99,8 @@ static int ch341_control_out(struct usb_
 	r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
 			    USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
 			    value, index, NULL, 0, DEFAULT_TIMEOUT);
+	if (r < 0)
+		dev_err(&dev->dev, "failed to send control message: %d\n", r);
 
 	return r;
 }
@@ -116,7 +118,20 @@ 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);
-	return r;
+	if (r < bufsize) {
+		if (r >= 0) {
+			dev_err(&dev->dev,
+				"short control message received (%d < %u)\n",
+				r, bufsize);
+			r = -EIO;
+		}
+
+		dev_err(&dev->dev, "failed to receive control message: %d\n",
+			r);
+		return r;
+	}
+
+	return 0;
 }
 
 static int ch341_set_baudrate(struct usb_device *dev,
@@ -158,9 +173,9 @@ static int ch341_set_handshake(struct us
 
 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 {
+	const unsigned int size = 2;
 	char *buffer;
 	int r;
-	const unsigned size = 8;
 	unsigned long flags;
 
 	buffer = kmalloc(size, GFP_KERNEL);
@@ -171,14 +186,9 @@ static int ch341_get_status(struct usb_d
 	if (r < 0)
 		goto out;
 
-	/* setup the private status if available */
-	if (r == 2) {
-		r = 0;
-		spin_lock_irqsave(&priv->lock, flags);
-		priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
-		spin_unlock_irqrestore(&priv->lock, flags);
-	} else
-		r = -EPROTO;
+	spin_lock_irqsave(&priv->lock, flags);
+	priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
+	spin_unlock_irqrestore(&priv->lock, flags);
 
 out:	kfree(buffer);
 	return r;
@@ -188,9 +198,9 @@ out:	kfree(buffer);
 
 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 {
+	const unsigned int size = 2;
 	char *buffer;
 	int r;
-	const unsigned size = 8;
 
 	buffer = kmalloc(size, GFP_KERNEL);
 	if (!buffer)


Patches currently in stable-queue which might be from johan@kernel.org are

queue-4.4/usb-serial-ch341-fix-control-message-error-handling.patch
queue-4.4/usb-serial-ch341-fix-open-and-resume-after-b0.patch
queue-4.4/usb-serial-ch341-fix-open-error-handling.patch
queue-4.4/usb-serial-ch341-fix-initial-modem-control-state.patch
queue-4.4/usb-serial-kl5kusb105-fix-line-state-error-handling.patch
queue-4.4/usb-serial-ch341-fix-resume-after-reset.patch