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>

diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
index ca0ab5112efd6e152b0f5d6a6fd044da0bd33089..b7ba82960c7925c5d04eb898af55a95b3be058f4 100644 (file)
--- a/drivers/hid/hid-logitech-dj.c
+++ b/drivers/hid/hid-logitech-dj.c
@@ -238,13 +238,6 @@ static void logi_dj_recv_add_djhid_device(struct dj_receiver_dev *djrcv_dev,
                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__);
@@ -690,6 +683,12 @@ 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.
         */
+       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",
+                               __func__, dj_report->device_index);
+               return false;
+       }
 
        spin_lock_irqsave(&djrcv_dev->lock, flags);
        if (dj_report->report_id == REPORT_ID_DJ_SHORT) {