HID: logitech-hidpp: rework device validation

G920 device only advertises REPORT_ID_HIDPP_LONG and
REPORT_ID_HIDPP_VERY_LONG in its HID report descriptor, so querying
for REPORT_ID_HIDPP_SHORT with optional=false will always fail and
prevent G920 to be recognized as a valid HID++ device.

To fix this and improve some other aspects, modify
hidpp_validate_device() as follows:

  - Inline the code of hidpp_validate_report() to simplify
    distingushing between non-present and invalid report descriptors

  - Drop the check for id >= HID_MAX_IDS || id < 0 since all of our
    IDs are static and known to satisfy that at compile time

  - Change the algorithms to check all possible report
    types (including very long report) and deem the device as a valid
    HID++ device if it supports at least one

  - Treat invalid report length as a hard stop for the validation
    algorithm, meaning that if any of the supported reports has
    invalid length we assume the worst and treat the device as a
    generic HID device.

  - Fold initialization of hidpp->very_long_report_length into
    hidpp_validate_device() since it already fetches very long report
    length and validates its value

Fixes: fe3ee1ec007b ("HID: logitech-hidpp: allow non HID++ devices to be handled by this module")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204191
Reported-by: Sam Bazely <sambazley@fastmail.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Henrik Rydberg <rydberg@bitmath.org>
Cc: Pierre-Loup A. Griffais <pgriffais@valvesoftware.com>
Cc: Austin Palmer <austinp@valvesoftware.com>
Cc: linux-input@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org # 5.2+
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 8591158..6e669eb 100644 (file)
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -3498,34 +3498,45 @@ static int hidpp_get_report_length(struct hid_device *hdev, int id)
        return report->field[0]->report_count + 1;
 }
 
-static bool hidpp_validate_report(struct hid_device *hdev, int id,
-                                 int expected_length, bool optional)
+static bool hidpp_validate_device(struct hid_device *hdev)
 {
-       int report_length;
+       struct hidpp_device *hidpp = hid_get_drvdata(hdev);
+       int id, report_length, supported_reports = 0;
+
+       id = REPORT_ID_HIDPP_SHORT;
+       report_length = hidpp_get_report_length(hdev, id);
+       if (report_length) {
+               if (report_length < HIDPP_REPORT_SHORT_LENGTH)
+                       goto bad_device;
 
-       if (id >= HID_MAX_IDS || id < 0) {
-               hid_err(hdev, "invalid HID report id %u\n", id);
-               return false;
+               supported_reports++;
        }
 
+       id = REPORT_ID_HIDPP_LONG;
        report_length = hidpp_get_report_length(hdev, id);
-       if (!report_length)
-               return optional;
+       if (report_length) {
+               if (report_length < HIDPP_REPORT_LONG_LENGTH)
+                       goto bad_device;
 
-       if (report_length < expected_length) {
-               hid_warn(hdev, "not enough values in hidpp report %d\n", id);
-               return false;
+               supported_reports++;
        }
 
-       return true;
-}
+       id = REPORT_ID_HIDPP_VERY_LONG;
+       report_length = hidpp_get_report_length(hdev, id);
+       if (report_length) {
+               if (report_length < HIDPP_REPORT_LONG_LENGTH ||
+                   report_length > HIDPP_REPORT_VERY_LONG_MAX_LENGTH)
+                       goto bad_device;
 
-static bool hidpp_validate_device(struct hid_device *hdev)
-{
-       return hidpp_validate_report(hdev, REPORT_ID_HIDPP_SHORT,
-                                    HIDPP_REPORT_SHORT_LENGTH, false) &&
-              hidpp_validate_report(hdev, REPORT_ID_HIDPP_LONG,
-                                    HIDPP_REPORT_LONG_LENGTH, true);
+               supported_reports++;
+               hidpp->very_long_report_length = report_length;
+       }
+
+       return supported_reports;
+
+bad_device:
+       hid_warn(hdev, "not enough values in hidpp report %d\n", id);
+       return false;
 }
 
 static bool hidpp_application_equals(struct hid_device *hdev,
@@ -3572,11 +3583,6 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
                return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
        }
 
-       hidpp->very_long_report_length =
-               hidpp_get_report_length(hdev, REPORT_ID_HIDPP_VERY_LONG);
-       if (hidpp->very_long_report_length > HIDPP_REPORT_VERY_LONG_MAX_LENGTH)
-               hidpp->very_long_report_length = HIDPP_REPORT_VERY_LONG_MAX_LENGTH;
-
        if (id->group == HID_GROUP_LOGITECH_DJ_DEVICE)
                hidpp->quirks |= HIDPP_QUIRK_UNIFYING;