patch "USB: serial: cyberjack: fix write-URB completion race" added to usb-linus

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

USB: serial: cyberjack: fix write-URB completion race

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 985616f0457d9f555fff417d0da56174f70cc14f Mon Sep 17 00:00:00 2001
From: Johan Hovold <[email protected]>
Date: Mon, 26 Oct 2020 09:25:48 +0100
Subject: USB: serial: cyberjack: fix write-URB completion race

The write-URB busy flag was being cleared before the completion handler was done with the URB, something which could lead to corrupt transfers due to a racing write request if the URB is resubmitted.

---
 drivers/usb/serial/cyberjack.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

index 821970609695..2e40908963da 100644
@@ -357,11 +357,12 @@ static void cyberjack_write_bulk_callback(struct urb *urb)
 	struct device *dev = &port->dev;
 	int status = urb->status;
 	unsigned long flags;
+	bool resubmitted = false;
 
-	set_bit(0, &port->write_urbs_free);
 	if (status) {
 		dev_dbg(dev, "%s - nonzero write bulk status received: %d\n",
 			__func__, status);
+		set_bit(0, &port->write_urbs_free);
 		return;
 	}
 

@@ -394,6 +395,8 @@ static void cyberjack_write_bulk_callback(struct urb *urb)
 			goto exit;
 		}
 
+		resubmitted = true;
+
 		dev_dbg(dev, "%s - priv->wrsent=%d\n", __func__, priv->wrsent);
 		dev_dbg(dev, "%s - priv->wrfilled=%d\n", __func__, priv->wrfilled);
 

@@ -410,6 +413,8 @@ static void cyberjack_write_bulk_callback(struct urb *urb)
 
 exit:
 	spin_unlock_irqrestore(&priv->lock, flags);
+	if (!resubmitted)
+		set_bit(0, &port->write_urbs_free);
 	usb_serial_port_softint(port);
 }
 

2.29.2