Commit message: USB: io_ti: Fix NULL dereference in chase_port()

The tty is NULL when the port is hanging up.
chase_port() needs to check for this.

This patch is intended for stable series.
The behavior was observed and tested in Linux 3.2 and 3.7.1.

Johan Hovold submitted a more elaborate patch for the mainline kernel.

[   56.277883] usb 1-1: edge_bulk_in_callback - nonzero read bulk status received: -84
[   56.278811] usb 1-1: USB disconnect, device number 3
[   56.278856] usb 1-1: edge_bulk_in_callback - stopping read!
[   56.279562] BUG: unable to handle kernel NULL pointer dereference at 00000000000001c8
[   56.280536] IP: [<ffffffff8144e62a>] _raw_spin_lock_irqsave+0x19/0x35
[   56.281212] PGD 1dc1b067 PUD 1e0f7067 PMD 0
[   56.282085] Oops: 0002 [#1] SMP
[   56.282744] Modules linked in:
[   56.283512] CPU 1
[   56.283512] Pid: 25, comm: khubd Not tainted 3.7.1 #1 innotek GmbH VirtualBox/VirtualBox
[   56.283512] RIP: 0010:[<ffffffff8144e62a>]  [<ffffffff8144e62a>] _raw_spin_lock_irqsave+0x19/0x35
[   56.283512] RSP: 0018:ffff88001fa99ab0  EFLAGS: 00010046
[   56.283512] RAX: 0000000000000046 RBX: 00000000000001c8 RCX: 0000000000640064
[   56.283512] RDX: 0000000000010000 RSI: ffff88001fa99b20 RDI: 00000000000001c8
[   56.283512] RBP: ffff88001fa99b20 R08: 0000000000000000 R09: 0000000000000000
[   56.283512] R10: 0000000000000000 R11: ffffffff812fcb4c R12: ffff88001ddf53c0
[   56.283512] R13: 0000000000000000 R14: 00000000000001c8 R15: ffff88001e19b9f4
[   56.283512] FS:  0000000000000000(0000) GS:ffff88001fd00000(0000) knlGS:0000000000000000
[   56.283512] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[   56.283512] CR2: 00000000000001c8 CR3: 000000001dc51000 CR4: 00000000000006e0
[   56.283512] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   56.283512] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[   56.283512] Process khubd (pid: 25, threadinfo ffff88001fa98000, task ffff88001fa94f80)
[   56.283512] Stack:
[   56.283512]  0000000000000046 00000000000001c8 ffffffff810578ec ffffffff812fcb4c
[   56.283512]  ffff88001e19b980 0000000000002710 ffffffff812ffe81 0000000000000001
[   56.283512]  ffff88001fa94f80 0000000000000202 ffffffff00000001 0000000000000296
[   56.283512] Call Trace:
[   56.283512]  [<ffffffff810578ec>] ? add_wait_queue+0x12/0x3c
[   56.283512]  [<ffffffff812fcb4c>] ? usb_serial_port_work+0x28/0x28
[   56.283512]  [<ffffffff812ffe81>] ? chase_port+0x84/0x2d6
[   56.283512]  [<ffffffff81063f27>] ? try_to_wake_up+0x199/0x199
[   56.283512]  [<ffffffff81263a5c>] ? tty_ldisc_hangup+0x222/0x298
[   56.283512]  [<ffffffff81300171>] ? edge_close+0x64/0x129
[   56.283512]  [<ffffffff810612f7>] ? __wake_up+0x35/0x46
[   56.283512]  [<ffffffff8106135b>] ? should_resched+0x5/0x23
[   56.283512]  [<ffffffff81264916>] ? tty_port_shutdown+0x39/0x44
[   56.283512]  [<ffffffff812fcb4c>] ? usb_serial_port_work+0x28/0x28
[   56.283512]  [<ffffffff8125d38c>] ? __tty_hangup+0x307/0x351
[   56.283512]  [<ffffffff812e6ddc>] ? usb_hcd_flush_endpoint+0xde/0xed
[   56.283512]  [<ffffffff8144e625>] ? _raw_spin_lock_irqsave+0x14/0x35
[   56.283512]  [<ffffffff812fd361>] ? usb_serial_disconnect+0x57/0xc2
[   56.283512]  [<ffffffff812ea99b>] ? usb_unbind_interface+0x5c/0x131
[   56.283512]  [<ffffffff8128d738>] ? __device_release_driver+0x7f/0xd5
[   56.283512]  [<ffffffff8128d9cd>] ? device_release_driver+0x1a/0x25
[   56.283512]  [<ffffffff8128d393>] ? bus_remove_device+0xd2/0xe7
[   56.283512]  [<ffffffff8128b7a3>] ? device_del+0x119/0x167
[   56.283512]  [<ffffffff812e8d9d>] ? usb_disable_device+0x6a/0x180
[   56.283512]  [<ffffffff812e2ae0>] ? usb_disconnect+0x81/0xe6
[   56.283512]  [<ffffffff812e4435>] ? hub_thread+0x577/0xe82
[   56.283512]  [<ffffffff8144daa7>] ? __schedule+0x490/0x4be
[   56.283512]  [<ffffffff8105798f>] ? abort_exclusive_wait+0x79/0x79
[   56.283512]  [<ffffffff812e3ebe>] ? usb_remote_wakeup+0x2f/0x2f
[   56.283512]  [<ffffffff812e3ebe>] ? usb_remote_wakeup+0x2f/0x2f
[   56.283512]  [<ffffffff810570b4>] ? kthread+0x81/0x89
[   56.283512]  [<ffffffff81057033>] ? __kthread_parkme+0x5c/0x5c
[   56.283512]  [<ffffffff8145387c>] ? ret_from_fork+0x7c/0xb0
[   56.283512]  [<ffffffff81057033>] ? __kthread_parkme+0x5c/0x5c
[   56.283512] Code: 8b 7c 24 08 e8 17 0b c3 ff 48 8b 04 24 48 83 c4 10 c3 53 48 89 fb 41 50 e8 e0 0a c3 ff 48 89 04 24 e8 e7 0a c3 ff ba 00 00 01 00
<f0> 0f c1 13 48 8b 04 24 89 d1 c1 ea 10 66 39 d1 74 07 f3 90 66
[   56.283512] RIP  [<ffffffff8144e62a>] _raw_spin_lock_irqsave+0x19/0x35
[   56.283512]  RSP <ffff88001fa99ab0>
[   56.283512] CR2: 00000000000001c8
[   56.283512] ---[ end trace 49714df27e1679ce ]---

Signed-off-by: Wolfgang Frisch <wfpub@roembden.net>
Cc: Johan Hovold <jhovold@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CVE: CVE-2013-1774
CWE: CWE-264
Vulnerability description: The chase_port function in drivers/usb/serial/io_ti.c in the Linux kernel before 3.7.4 allows local users to cause a denial of service (NULL pointer dereference and system crash) via an attempted /dev/ttyUSB read or write operation on a disconnected Edgeport USB serial converter.

Project: linux
File: io_ti.c

static int edge_create_sysfs_attrs(struct usb_serial_port *port)
{
	return device_create_file(&port->dev, &dev_attr_uart_mode);
}

Project: linux

static int edge_ioctl(struct tty_struct *tty,
					unsigned int cmd, unsigned long arg)
{
	struct usb_serial_port *port = tty->driver_data;
	struct edgeport_port *edge_port = usb_get_serial_port_data(port);
	struct async_icount cnow;
	struct async_icount cprev;

	dev_dbg(&port->dev, "%s - port %d, cmd = 0x%x\n", __func__, port->number, cmd);

	switch (cmd) {
	case TIOCGSERIAL:
		dev_dbg(&port->dev, "%s - TIOCGSERIAL\n", __func__);
		return get_serial_info(edge_port,
				(struct serial_struct __user *) arg);
	case TIOCMIWAIT:
		dev_dbg(&port->dev, "%s - TIOCMIWAIT\n", __func__);
		cprev = edge_port->icount;
		while (1) {
			interruptible_sleep_on(&edge_port->delta_msr_wait);
			/* see if a signal did it */
			if (signal_pending(current))
				return -ERESTARTSYS;
			cnow = edge_port->icount;
			if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
			    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
				return -EIO; /* no change => error */
			if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
			    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
			    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
			    ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
				return 0;
			}
			cprev = cnow;
		}
		/* not reached */
		break;
	}
	return -ENOIOCTLCMD;
}

Project: linux

static int edge_port_probe(struct usb_serial_port *port)
{
	struct edgeport_port *edge_port;
	int ret;

	edge_port = kzalloc(sizeof(*edge_port), GFP_KERNEL);
	if (!edge_port)
		return -ENOMEM;

	ret = kfifo_alloc(&edge_port->write_fifo, EDGE_OUT_BUF_SIZE,
								GFP_KERNEL);
	if (ret) {
		kfree(edge_port);
		return -ENOMEM;
	}

	spin_lock_init(&edge_port->ep_lock);
	edge_port->port = port;
	edge_port->edge_serial = usb_get_serial_data(port->serial);
	edge_port->bUartMode = default_uart_mode;

	usb_set_serial_port_data(port, edge_port);

	ret = edge_create_sysfs_attrs(port);
	if (ret) {
		kfifo_free(&edge_port->write_fifo);
		kfree(edge_port);
		return ret;
	}

	return 0;
}

Project: linux

static void edge_release(struct usb_serial *serial)
{
	kfree(usb_get_serial_data(serial));
}

Project: linux

static void edge_send(struct tty_struct *tty)
{
	struct usb_serial_port *port = tty->driver_data;
	int count, result;
	struct edgeport_port *edge_port = usb_get_serial_port_data(port);
	unsigned long flags;

	spin_lock_irqsave(&edge_port->ep_lock, flags);

	if (edge_port->ep_write_urb_in_use) {
		spin_unlock_irqrestore(&edge_port->ep_lock, flags);
		return;
	}

	count = kfifo_out(&edge_port->write_fifo,
				port->write_urb->transfer_buffer,
				port->bulk_out_size);

	if (count == 0) {
		spin_unlock_irqrestore(&edge_port->ep_lock, flags);
		return;
	}

	edge_port->ep_write_urb_in_use = 1;

	spin_unlock_irqrestore(&edge_port->ep_lock, flags);

	usb_serial_debug_data(&port->dev, __func__, count, port->write_urb->transfer_buffer);

	/* set up our urb */
	port->write_urb->transfer_buffer_length = count;

	/* send the data out the bulk port */
	result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
	if (result) {
		dev_err_console(port,
			"%s - failed submitting write urb, error %d\n",
				__func__, result);
		edge_port->ep_write_urb_in_use = 0;
		/* TODO: reschedule edge_send */
	} else
		edge_port->icount.tx += count;

	/* wakeup any process waiting for writes to complete */
	/* there is now more room in the buffer for new writes */
	if (tty)
		tty_wakeup(tty);
}

Project: linux

static int edge_startup(struct usb_serial *serial)
{
	struct edgeport_serial *edge_serial;
	int status;

	/* create our private serial structure */
	edge_serial = kzalloc(sizeof(struct edgeport_serial), GFP_KERNEL);
	if (edge_serial == NULL) {
		dev_err(&serial->dev->dev, "%s - Out of memory\n", __func__);
		return -ENOMEM;
	}
	mutex_init(&edge_serial->es_lock);
	edge_serial->serial = serial;
	usb_set_serial_data(serial, edge_serial);

	status = download_fw(edge_serial);
	if (status) {
		kfree(edge_serial);
		return status;
	}

	return 0;
}

Project: linux

static int purge_port(struct usb_serial_port *port, __u16 mask)
{
	int port_number = port->number - port->serial->minor;

	dev_dbg(&port->dev, "%s - port %d, mask %x\n", __func__, port_number, mask);

	return send_cmd(port->serial->dev,
					UMPC_PURGE_PORT,
					(__u8)(UMPM_UART1_PORT + port_number),
					mask,
					NULL,
					0);
}

Project: linux
File: io_ti.c

static int restart_read(struct edgeport_port *edge_port)
{
	struct urb *urb;
	int status = 0;
	unsigned long flags;

	spin_lock_irqsave(&edge_port->ep_lock, flags);

	if (edge_port->ep_read_urb_state == EDGE_READ_URB_STOPPED) {
		urb = edge_port->port->read_urb;
		status = usb_submit_urb(urb, GFP_ATOMIC);
	}
	edge_port->ep_read_urb_state = EDGE_READ_URB_RUNNING;
	edge_port->shadow_mcr |= MCR_RTS;

	spin_unlock_irqrestore(&edge_port->ep_lock, flags);

	return status;
}

Project: linux

static int send_cmd(struct usb_device *dev, __u8 command,
				__u8 moduleid, __u16 value, u8 *data,
				int size)
{
	return ti_vsend_sync(dev, command, value, moduleid, data, size);
}

Project: linux
File: io_ti.c

static void stop_read(struct edgeport_port *edge_port)
{
	unsigned long flags;

	spin_lock_irqsave(&edge_port->ep_lock, flags);

	if (edge_port->ep_read_urb_state == EDGE_READ_URB_RUNNING)
		edge_port->ep_read_urb_state = EDGE_READ_URB_STOPPING;
	edge_port->shadow_mcr &= ~MCR_RTS;

	spin_unlock_irqrestore(&edge_port->ep_lock, flags);
}