Syzbot found a buffer underflow in __hid_request(). Add a related test case for it.
It's not perfect, but it allows to catch a corner case when a report descriptor is crafted so that it has a size of 0.
Signed-off-by: Benjamin Tissoires bentiss@kernel.org --- tools/testing/selftests/hid/tests/test_mouse.py | 70 +++++++++++++++++++++++++ 1 file changed, 70 insertions(+)
diff --git a/tools/testing/selftests/hid/tests/test_mouse.py b/tools/testing/selftests/hid/tests/test_mouse.py index 66daf7e5975ca50f0b065080669d7f6123fb177f..eb4e15a0e53bd5f3c8e0ea02365ff9da7eead93d 100644 --- a/tools/testing/selftests/hid/tests/test_mouse.py +++ b/tools/testing/selftests/hid/tests/test_mouse.py @@ -439,6 +439,68 @@ class BadResolutionMultiplierMouse(ResolutionMultiplierMouse): return 32 # EPIPE
+class BadReportDescriptorMouse(BaseMouse): + """ + This "device" was one autogenerated by syzbot. There are a lot of issues in + it, and the most problematic is that it declares features that have no + size. + + This leads to report->size being set to 0 and can mess up with usbhid + internals. Fortunately, uhid merely passes the incoming buffer, without + touching it so a buffer of size 0 will be translated to [] without + triggering a kernel oops. + + Because the report descriptor is wrong, no input are created, and we need + to tweak a little bit the parameters to make it look correct. + """ + + # fmt: off + report_descriptor = [ + 0x96, 0x01, 0x00, # Report Count (1) 0 + 0x06, 0x01, 0x00, # Usage Page (Generic Desktop) 3 + # 0x03, 0x00, 0x00, 0x00, 0x00, # Ignored by the kernel somehow + 0x2a, 0x90, 0xa0, # Usage Maximum (41104) 6 + 0x27, 0x00, 0x00, 0x00, 0x00, # Logical Maximum (0) 9 + 0xb3, 0x81, 0x3e, 0x25, 0x03, # Feature (Cnst,Arr,Abs,Vol) 14 + 0x1b, 0xdd, 0xe8, 0x40, 0x50, # Usage Minimum (1346431197) 19 + 0x3b, 0x5d, 0x8c, 0x3d, 0xda, # Designator Index 24 + ] + # fmt: on + + def __init__( + self, rdesc=report_descriptor, name=None, input_info=(3, 0x045E, 0x07DA) + ): + super().__init__(rdesc, name, input_info) + self.high_resolution_report_called = False + + def get_evdev(self, application=None): + assert self._input_nodes is None + return ( + "Ok" # should be a list or None, but both would fail, so abusing the system + ) + + def next_sync_events(self, application=None): + # there are no evdev nodes, so no events + return [] + + def is_ready(self): + # we wait for the SET_REPORT command to come + return self.high_resolution_report_called + + def set_report(self, req, rnum, rtype, data): + if rtype != self.UHID_FEATURE_REPORT: + raise InvalidHIDCommunication(f"Unexpected report type: {rtype}") + if rnum != 0x0: + raise InvalidHIDCommunication(f"Unexpected report number: {rnum}") + + if len(data) != 1: + raise InvalidHIDCommunication(f"Unexpected data: {data}, expected '[0]'") + + self.high_resolution_report_called = True + + return 0 + + class ResolutionMultiplierHWheelMouse(TwoWheelMouse): # fmt: off report_descriptor = [ @@ -975,3 +1037,11 @@ class TestMiMouse(TestWheelMouse): # assert below print out the real error pass assert remaining == [] + + +class TestBadReportDescriptorMouse(base.BaseTestCase.TestUhid): + def create_device(self): + return BadReportDescriptorMouse() + + def assertName(self, uhdev): + pass