[PATCH] USB: serial: suppress driver bind attributes

[Johan Hovold <johan@kernel.org>]

USB-serial drivers must not be unbound from their ports before the
corresponding USB driver is unbound from the parent interface so
suppress the bind and unbind attributes.

Unbinding a serial driver while it's port is open is a sure way to
trigger a crash as any driver state is released on unbind while port
hangup is handled on the parent USB interface level. Drivers for
multiport devices where ports share a resource such as an interrupt
endpoint also generally cannot handle individual ports going away.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/usb-serial.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 8f066bb55d7d..dc7a65b9ec98 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -1317,6 +1317,9 @@ static int usb_serial_register(struct usb_serial_driver *driver)
 		return -EINVAL;
 	}
 
+	/* Prevent individual ports from being unbound. */
+	driver->driver.suppress_bind_attrs = true;
+
 	usb_serial_operations_init(driver);
 
 	/* Add this device to our list of devices */
-- 
2.24.1