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

PATCH In review Johan Hovold 2 participants 3 messages Oct 26, 2020 – Nov 4, 2020

Subsystems (3)
Stable branch USB USB serial
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Johan Hovold

author maintainer
#0 lore raw

PATCH 1/1 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.

Fixes 507ca9bc0476 ("[PATCH] USB: add ability for usb-serial drivers to determine if their write urb is currently being used.")
Cc stable <[email protected]> # 2.6.13
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/usb/serial/cyberjack.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
drivers/usb/serial/cyberjack.c +6 -1
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);
 }
Signature · 1 line
2.26.2
maintainer Reviewed-by on v1 1/1
#1 lore raw
Quoted 10 lines · Johan Hovold

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.

Fixes 507ca9bc0476 ("[PATCH] USB: add ability for usb-serial drivers to determine if their write urb is currently being used.")
Cc stable <[email protected]> # 2.6.13
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/usb/serial/cyberjack.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
Reviewed-by Greg Kroah-Hartman <[email protected]>
author maintainer Applied
#2 lore raw
Quoted 5 lines · Greg Kroah-Hartman
Quoted 4 lines · Johan Hovold

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.

Quoted 8 lines
Quoted 6 lines
Fixes 507ca9bc0476 ("[PATCH] USB: add ability for usb-serial drivers to determine if their write urb is currently being used.")
Cc stable <[email protected]> # 2.6.13
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/usb/serial/cyberjack.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
Reviewed-by Greg Kroah-Hartman <[email protected]>

Thanks, applied for 5.10-rc.

Johan