linux-kernel - [PATCH 3.16 192/245] USB: serial: suppress driver bind attributes

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Message-ID: <lsq.1587683028.829097850@decadent.org.uk>
Date:   Fri, 24 Apr 2020 00:06:59 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Johan Hovold" <johan@...nel.org>
Subject: [PATCH 3.16 192/245] USB: serial: suppress driver bind attributes

3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@...nel.org>

commit fdb838efa31e1ed9a13ae6ad0b64e30fdbd00570 upstream.

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.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Johan Hovold <johan@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/serial/usb-serial.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -1337,6 +1337,9 @@ static int usb_serial_register(struct us
 		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 */