linux-kernel - [PATCH 3.2 074/199] USB: serial: mos7720: fix NULL-deref at open

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Message-ID: <lsq.1489146370.251370533@decadent.org.uk>
Date:   Fri, 10 Mar 2017 11:46:10 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Johan Hovold" <johan@...nel.org>
Subject: [PATCH 3.2 074/199] USB: serial: mos7720: fix NULL-deref at open

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

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

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

commit b05aebc25fdc5aeeac3ee29f0dc9f58dd07c13cc upstream.

Fix NULL-pointer dereference at port open if a device lacks the expected
bulk in and out endpoints.

Unable to handle kernel NULL pointer dereference at virtual address 00000030
...
[<bf071c20>] (mos7720_open [mos7720]) from [<bf0490e0>] (serial_port_activate+0x68/0x98 [usbserial])
[<bf0490e0>] (serial_port_activate [usbserial]) from [<c0470ca4>] (tty_port_open+0x9c/0xe8)
[<c0470ca4>] (tty_port_open) from [<bf049d98>] (serial_open+0x48/0x6c [usbserial])
[<bf049d98>] (serial_open [usbserial]) from [<c0469178>] (tty_open+0xcc/0x5cc)

Fixes: 0f64478cbc7a ("USB: add USB serial mos7720 driver")
Signed-off-by: Johan Hovold <johan@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/serial/mos7720.c | 5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -2079,6 +2079,11 @@ static int mos7720_startup(struct usb_se
 		return -ENODEV;
 	}

+	if (serial->num_bulk_in < 2 || serial->num_bulk_out < 2) {
+		dev_err(&serial->interface->dev, "missing bulk endpoints\n");
+		return -ENODEV;
+	}
+
 	product = le16_to_cpu(serial->dev->descriptor.idProduct);
 	dev = serial->dev;