HID: ntrig don't dereference unclaimed hidinput

Check before dereferencing field->hidinput to fix a reported invalid
deference bug.

Signed-off-by: Rafi Rubin <rafi@seas.upenn.edu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

1 files changed, 14 insertions, 1 deletions

diff --git a/usr/src/dkms_source_tree/hid-ntrig.c b/usr/src/dkms_source_tree/hid-ntrig.c
index 0fab58b..9e6b91e 100644
--- a/usr/src/dkms_source_tree/hid-ntrig.c
+++ b/usr/src/dkms_source_tree/hid-ntrig.c
@@ -332,8 +332,19 @@ static void report_frame(struct input_dev *input, struct ntrig_data *nd)
 static int ntrig_event (struct hid_device *hid, struct hid_field *field,
                         struct hid_usage *usage, __s32 value)
 {
-        struct input_dev *input = field->hidinput->input;
         struct ntrig_data *nd = hid_get_drvdata(hid);
+        struct input_dev *input;
+
+        /* Skip processing if not a claimed input */
+        if (!(hid->claimed & HID_CLAIMED_INPUT))
+                goto not_claimed_input;
+
+        /* This function is being called before the structures are fully
+         * initialized */
+        if(!(field->hidinput && field->hidinput->input))
+                return -EINVAL;
+
+        input = field->hidinput->input;
 
         /* No special handling needed for the pen */
         if (field->application == HID_DG_PEN)
@@ -377,6 +388,8 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
                 }
         }
 
+not_claimed_input:
+
         /* we have handled the hidinput part, now remains hiddev */
         if ((hid->claimed & HID_CLAIMED_HIDDEV) && hid->hiddev_hid_event)
                 hid->hiddev_hid_event(hid, field, usage, value);