linux-kernel - [PATCH 3.12 078/113] USB: serial: mos7840: fix another NULL-deref at open

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Message-Id: <082a7236ca46d594db12129bfa519a61ad513f3a.1488791431.git.jslaby@suse.cz>
Date:   Mon,  6 Mar 2017 10:11:42 +0100
From:   Jiri Slaby <jslaby@...e.cz>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 078/113] USB: serial: mos7840: fix another NULL-deref at open

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

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 5182c2cf2a9bfb7f066ef0bdd2bb6330b94dd74e upstream.

Fix another NULL-pointer dereference at open should a malicious device
lack an interrupt-in endpoint.

Note that the driver has a broken check for an interrupt-in endpoint
which means that an interrupt URB has never even been submitted.

Fixes: 3f5429746d91 ("USB: Moschip 7840 USB-Serial Driver")
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Johan Hovold <johan@...nel.org>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/usb/serial/mos7840.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index 0b1659026d85..fc052e4cc5b2 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -1031,6 +1031,7 @@ static int mos7840_open(struct tty_struct *tty, struct usb_serial_port *port)
 	 * (can't set it up in mos7840_startup as the structures *
 	 * were not set up at that time.)                        */
 	if (port0->open_ports == 1) {
+		/* FIXME: Buffer never NULL, so URB is not submitted. */
 		if (serial->port[0]->interrupt_in_buffer == NULL) {
 			/* set up interrupt urb */
 			usb_fill_int_urb(serial->port[0]->interrupt_in_urb,
@@ -2195,7 +2196,8 @@ static int mos7840_calc_num_ports(struct usb_serial *serial)
 static int mos7840_attach(struct usb_serial *serial)
 {
 	if (serial->num_bulk_in < serial->num_ports ||
-			serial->num_bulk_out < serial->num_ports) {
+			serial->num_bulk_out < serial->num_ports ||
+			serial->num_interrupt_in < 1) {
 		dev_err(&serial->interface->dev, "missing endpoints\n");
 		return -ENODEV;
 	}
-- 
2.12.0