Code: static void logi_dj_recv_add_djhid_device(struct dj_receiver_dev *djrcv_dev,
					  struct dj_report *dj_report)
{
	/* Called in delayed work context */
	struct hid_device *djrcv_hdev = djrcv_dev->hdev;
	struct usb_interface *intf = to_usb_interface(djrcv_hdev->dev.parent);
	struct usb_device *usbdev = interface_to_usbdev(intf);
	struct hid_device *dj_hiddev;
	struct dj_device *dj_dev;

	/* Device index goes from 1 to 6, we need 3 bytes to store the
	 * semicolon, the index, and a null terminator
	 */
	unsigned char tmpstr[3];

	if (dj_report->report_params[DEVICE_PAIRED_PARAM_SPFUNCTION] &
	    SPFUNCTION_DEVICE_LIST_EMPTY) {
		dbg_hid("%s: device list is empty\n", __func__);
		djrcv_dev->querying_devices = false;
 		return;
 	}
 
	if ((dj_report->device_index < DJ_DEVICE_INDEX_MIN) ||
	    (dj_report->device_index > DJ_DEVICE_INDEX_MAX)) {
		dev_err(&djrcv_hdev->dev, "%s: invalid device index:%d\n",
			__func__, dj_report->device_index);
		return;
	}
 	if (djrcv_dev->paired_dj_devices[dj_report->device_index]) {
 		/* The device is already known. No need to reallocate it. */
 		dbg_hid("%s: device is already known\n", __func__);
		return;
	}

	dj_hiddev = hid_allocate_device();
	if (IS_ERR(dj_hiddev)) {
		dev_err(&djrcv_hdev->dev, "%s: hid_allocate_device failed\n",
			__func__);
		return;
	}

	dj_hiddev->ll_driver = &logi_dj_ll_driver;

	dj_hiddev->dev.parent = &djrcv_hdev->dev;
	dj_hiddev->bus = BUS_USB;
	dj_hiddev->vendor = le16_to_cpu(usbdev->descriptor.idVendor);
	dj_hiddev->product = le16_to_cpu(usbdev->descriptor.idProduct);
	snprintf(dj_hiddev->name, sizeof(dj_hiddev->name),
		"Logitech Unifying Device. Wireless PID:%02x%02x",
		dj_report->report_params[DEVICE_PAIRED_PARAM_EQUAD_ID_MSB],
		dj_report->report_params[DEVICE_PAIRED_PARAM_EQUAD_ID_LSB]);

	usb_make_path(usbdev, dj_hiddev->phys, sizeof(dj_hiddev->phys));
	snprintf(tmpstr, sizeof(tmpstr), ":%d", dj_report->device_index);
	strlcat(dj_hiddev->phys, tmpstr, sizeof(dj_hiddev->phys));

	dj_dev = kzalloc(sizeof(struct dj_device), GFP_KERNEL);

	if (!dj_dev) {
		dev_err(&djrcv_hdev->dev, "%s: failed allocating dj_device\n",
			__func__);
		goto dj_device_allocate_fail;
	}

	dj_dev->reports_supported = get_unaligned_le32(
		dj_report->report_params + DEVICE_PAIRED_RF_REPORT_TYPE);
	dj_dev->hdev = dj_hiddev;
	dj_dev->dj_receiver_dev = djrcv_dev;
	dj_dev->device_index = dj_report->device_index;
	dj_hiddev->driver_data = dj_dev;

	djrcv_dev->paired_dj_devices[dj_report->device_index] = dj_dev;

	if (hid_add_device(dj_hiddev)) {
		dev_err(&djrcv_hdev->dev, "%s: failed adding dj_device\n",
			__func__);
		goto hid_add_device_fail;
	}

	return;

hid_add_device_fail:
	djrcv_dev->paired_dj_devices[dj_report->device_index] = NULL;
	kfree(dj_dev);
dj_device_allocate_fail:
	hid_destroy_device(dj_hiddev);
}

Vulnerability Type: DoS Exec Code Overflow 
CWE ID: CWE-119
Summary: Array index error in the logi_dj_raw_event function in drivers/hid/hid-logitech-dj.c in the Linux kernel before 3.16.2 allows physically proximate attackers to execute arbitrary code or cause a denial of service (invalid kfree) via a crafted device that provides a malformed REPORT_TYPE_NOTIF_DEVICE_UNPAIRED value.
Commit Message: HID: logitech: perform bounds checking on device_id early enough

device_index is a char type and the size of paired_dj_deivces is 7
elements, therefore proper bounds checking has to be applied to
device_index before it is used.

We are currently performing the bounds checking in
logi_dj_recv_add_djhid_device(), which is too late, as malicious device
could send REPORT_TYPE_NOTIF_DEVICE_UNPAIRED early enough and trigger the
problem in one of the report forwarding functions called from
logi_dj_raw_event().

Fix this by performing the check at the earliest possible ocasion in
logi_dj_raw_event().

Cc: stable@vger.kernel.org
Reported-by: Ben Hawkes <hawkes@google.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>