linux-kernel - [PATCH 3.2 081/199] USB: serial: oti6858: fix NULL-deref at open

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Message-ID: <lsq.1489146370.537533275@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 3.2 081/199] USB: serial: oti6858: 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 5afeef2366db14587b65558bbfd5a067542e07fb upstream.

Fix NULL-pointer dereference in open() should the device lack the
expected endpoints:

Unable to handle kernel NULL pointer dereference at virtual address 00000030
...
PC is at oti6858_open+0x30/0x1d0 [oti6858]

Note that a missing interrupt-in endpoint would have caused open() to
fail.

Fixes: 49cdee0ed0fc ("USB: oti6858 usb-serial driver (in Nokia CA-42
cable)")
Signed-off-by: Johan Hovold <johan@...nel.org>
[bwh: Backported to 3.2: add this check to the existing
 usb_serial_driver::attach implementation]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/usb/serial/oti6858.c
+++ b/drivers/usb/serial/oti6858.c
@@ -347,9 +347,17 @@ static void send_data(struct work_struct
 static int oti6858_startup(struct usb_serial *serial)
 {
 	struct usb_serial_port *port = serial->port[0];
+	unsigned char num_ports = serial->num_ports;
 	struct oti6858_private *priv;
 	int i;
 
+	if (serial->num_bulk_in < num_ports ||
+			serial->num_bulk_out < num_ports ||
+			serial->num_interrupt_in < num_ports) {
+		dev_err(&serial->interface->dev, "missing endpoints\n");
+		return -ENODEV;
+	}
+
 	for (i = 0; i < serial->num_ports; ++i) {
 		priv = kzalloc(sizeof(struct oti6858_private), GFP_KERNEL);
 		if (!priv)