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Subject[PATCH 4.14 39/48] USB: serial: cyberjack: fix write-URB completion race
Date
From: Johan Hovold <johan@kernel.org>

commit 985616f0457d9f555fff417d0da56174f70cc14f upstream.

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 <stable@vger.kernel.org> # 2.6.13
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/usb/serial/cyberjack.c
+++ b/drivers/usb/serial/cyberjack.c
@@ -358,11 +358,12 @@ static void cyberjack_write_bulk_callbac
struct cyberjack_private *priv = usb_get_serial_port_data(port);
struct device *dev = &port->dev;
int status = urb->status;
+ 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;
}

@@ -395,6 +396,8 @@ static void cyberjack_write_bulk_callbac
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);

@@ -411,6 +414,8 @@ static void cyberjack_write_bulk_callbac

exit:
spin_unlock(&priv->lock);
+ if (!resubmitted)
+ set_bit(0, &port->write_urbs_free);
usb_serial_port_softint(port);
}


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