test_usb_crash.py

  1#!/bin/env python3
  2# SPDX-License-Identifier: GPL-2.0
  3# -*- coding: utf-8 -*-
  4#
  5# Copyright (c) 2021 Benjamin Tissoires <benjamin.tissoires@gmail.com>
  6# Copyright (c) 2021 Red Hat, Inc.
  7#
  8
  9# This is to ensure we don't crash when emulating USB devices
 10
 11from . import base
 12import pytest
 13import logging
 14
 15logger = logging.getLogger("hidtools.test.usb")
 16
 17
 18class USBDev(base.UHIDTestDevice):
 19    # fmt: off
 20    report_descriptor = [
 21        0x05, 0x01,  # .Usage Page (Generic Desktop)        0
 22        0x09, 0x02,  # .Usage (Mouse)                       2
 23        0xa1, 0x01,  # .Collection (Application)            4
 24        0x09, 0x02,  # ..Usage (Mouse)                      6
 25        0xa1, 0x02,  # ..Collection (Logical)               8
 26        0x09, 0x01,  # ...Usage (Pointer)                   10
 27        0xa1, 0x00,  # ...Collection (Physical)             12
 28        0x05, 0x09,  # ....Usage Page (Button)              14
 29        0x19, 0x01,  # ....Usage Minimum (1)                16
 30        0x29, 0x03,  # ....Usage Maximum (3)                18
 31        0x15, 0x00,  # ....Logical Minimum (0)              20
 32        0x25, 0x01,  # ....Logical Maximum (1)              22
 33        0x75, 0x01,  # ....Report Size (1)                  24
 34        0x95, 0x03,  # ....Report Count (3)                 26
 35        0x81, 0x02,  # ....Input (Data,Var,Abs)             28
 36        0x75, 0x05,  # ....Report Size (5)                  30
 37        0x95, 0x01,  # ....Report Count (1)                 32
 38        0x81, 0x03,  # ....Input (Cnst,Var,Abs)             34
 39        0x05, 0x01,  # ....Usage Page (Generic Desktop)     36
 40        0x09, 0x30,  # ....Usage (X)                        38
 41        0x09, 0x31,  # ....Usage (Y)                        40
 42        0x15, 0x81,  # ....Logical Minimum (-127)           42
 43        0x25, 0x7f,  # ....Logical Maximum (127)            44
 44        0x75, 0x08,  # ....Report Size (8)                  46
 45        0x95, 0x02,  # ....Report Count (2)                 48
 46        0x81, 0x06,  # ....Input (Data,Var,Rel)             50
 47        0xc0,        # ...End Collection                    52
 48        0xc0,        # ..End Collection                     53
 49        0xc0,        # .End Collection                      54
 50    ]
 51    # fmt: on
 52
 53    def __init__(self, name=None, input_info=None):
 54        super().__init__(
 55            name, "Mouse", input_info=input_info, rdesc=USBDev.report_descriptor
 56        )
 57
 58    # skip witing for udev events, it's likely that the report
 59    # descriptor is wrong
 60    def is_ready(self):
 61        return True
 62
 63    # we don't have an evdev node here, so paper over
 64    # the checks
 65    def get_evdev(self, application=None):
 66        return "OK"
 67
 68
 69class TestUSBDevice(base.BaseTestCase.TestUhid):
 70    """
 71    Test class to test if an emulated USB device crashes
 72    the kernel.
 73    """
 74
 75    # conftest.py is generating the following fixture:
 76    #
 77    # @pytest.fixture(params=[('modulename', 1, 2)])
 78    # def usbVidPid(self, request):
 79    #     return request.param
 80
 81    @pytest.fixture()
 82    def new_uhdev(self, usbVidPid, request):
 83        self.module, self.vid, self.pid = usbVidPid
 84        self._load_kernel_module(None, self.module)
 85        return USBDev(input_info=(3, self.vid, self.pid))
 86
 87    def test_creation(self):
 88        """
 89        inject the USB dev through uhid and immediately see if there is a crash:
 90
 91        uhid can create a USB device with the BUS_USB bus, and some
 92        drivers assume that they can then access USB related structures
 93        when they are actually provided a uhid device. This leads to
 94        a crash because those access result in a segmentation fault.
 95
 96        The kernel should not crash on any (random) user space correct
 97        use of its API. So run through all available modules and declared
 98        devices to see if we can generate a uhid device without a crash.
 99
100        The test is empty as the fixture `check_taint` is doing the job (and
101        honestly, when the kernel crashes, the whole machine freezes).
102        """
103        assert True