Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Content-Type: text/plain; charset="UTF-8"
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
MIME-Version: 1.0
From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, Denis Kirjanov <kda@linux-powerpc.org>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Johan Hovold" <johan@kernel.org>
Date:   Fri, 24 Apr 2020 00:06:59 +0100
Message-ID: <lsq.1587683028.829097850@decadent.org.uk>
Subject: [PATCH 3.16 192/245] USB: serial: suppress driver bind attributes
In-Reply-To: <lsq.1587683027.831233700@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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

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

From: Johan Hovold <johan@kernel.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@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.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 */