HID: logitech-dj: prevent false errors to be shown

Commit "HID: logitech: perform bounds checking on device_id early
enough" unfortunately leaks some errors to dmesg which are not real
ones:
- if the report is not a DJ one, then there is not point in checking
  the device_id
- the receiver (index 0) can also receive some notifications which
  can be safely ignored given the current implementation

Move out the test regarding the report_id and also discards
printing errors when the receiver got notified.

Fixes: ad3e14d7c5268c2e24477c6ef54bbdf88add5d36

Cc: stable@vger.kernel.org
Reported-and-tested-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

2 files changed, 26 insertions, 18 deletions

diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
index b7ba82960c79..9bf8637747a5 100644
--- a/drivers/hid/hid-logitech-dj.c
+++ b/drivers/hid/hid-logitech-dj.c
@@ -656,7 +656,6 @@ static int logi_dj_raw_event(struct hid_device *hdev,
         struct dj_receiver_dev *djrcv_dev = hid_get_drvdata(hdev);
         struct dj_report *dj_report = (struct dj_report *) data;
         unsigned long flags;
-        bool report_processed = false;
 
         dbg_hid("%s, size:%d\n", __func__, size);
 
@@ -683,34 +682,42 @@ static int logi_dj_raw_event(struct hid_device *hdev,
          * device (via hid_input_report() ) and return 1 so hid-core does not do
          * anything else with it.
          */
+
+        /* case 1) */
+        if (data[0] != REPORT_ID_DJ_SHORT)
+                return false;
+
         if ((dj_report->device_index < DJ_DEVICE_INDEX_MIN) ||
             (dj_report->device_index > DJ_DEVICE_INDEX_MAX)) {
-                dev_err(&hdev->dev, "%s: invalid device index:%d\n",
+                /*
+                 * Device index is wrong, bail out.
+                 * This driver can ignore safely the receiver notifications,
+                 * so ignore those reports too.
+                 */
+                if (dj_report->device_index != DJ_RECEIVER_INDEX)
+                        dev_err(&hdev->dev, "%s: invalid device index:%d\n",
                                 __func__, dj_report->device_index);
                 return false;
         }
 
         spin_lock_irqsave(&djrcv_dev->lock, flags);
-        if (dj_report->report_id == REPORT_ID_DJ_SHORT) {
-                switch (dj_report->report_type) {
-                case REPORT_TYPE_NOTIF_DEVICE_PAIRED:
-                case REPORT_TYPE_NOTIF_DEVICE_UNPAIRED:
-                        logi_dj_recv_queue_notification(djrcv_dev, dj_report);
-                        break;
-                case REPORT_TYPE_NOTIF_CONNECTION_STATUS:
-                        if (dj_report->report_params[CONNECTION_STATUS_PARAM_STATUS] ==
-                            STATUS_LINKLOSS) {
-                                logi_dj_recv_forward_null_report(djrcv_dev, dj_report);
-                        }
-                        break;
-                default:
-                        logi_dj_recv_forward_report(djrcv_dev, dj_report);
+        switch (dj_report->report_type) {
+        case REPORT_TYPE_NOTIF_DEVICE_PAIRED:
+        case REPORT_TYPE_NOTIF_DEVICE_UNPAIRED:
+                logi_dj_recv_queue_notification(djrcv_dev, dj_report);
+                break;
+        case REPORT_TYPE_NOTIF_CONNECTION_STATUS:
+                if (dj_report->report_params[CONNECTION_STATUS_PARAM_STATUS] ==
+                    STATUS_LINKLOSS) {
+                        logi_dj_recv_forward_null_report(djrcv_dev, dj_report);
                 }
-                report_processed = true;
+                break;
+        default:
+                logi_dj_recv_forward_report(djrcv_dev, dj_report);
         }
         spin_unlock_irqrestore(&djrcv_dev->lock, flags);
 
-        return report_processed;
+        return true;
 }
 
 static int logi_dj_probe(struct hid_device *hdev,
diff --git a/drivers/hid/hid-logitech-dj.h b/drivers/hid/hid-logitech-dj.h
index 4a4000340ce1..daeb0aa4bee9 100644
--- a/drivers/hid/hid-logitech-dj.h
+++ b/drivers/hid/hid-logitech-dj.h
@@ -27,6 +27,7 @@
 
 #define DJ_MAX_PAIRED_DEVICES                   6
 #define DJ_MAX_NUMBER_NOTIFICATIONS             8
+#define DJ_RECEIVER_INDEX                       0
 #define DJ_DEVICE_INDEX_MIN                     1
 #define DJ_DEVICE_INDEX_MAX                     6