HID: wiimote: discard invalid EXT data reports

If an extension device isn't initialized properly, or during hardware
initialization, a device might send extension data which is all 0xff.
This is ambigious because this is also a valid normal data report. But
it is impossible, under normal conditions, to trigger valid reports with
all 0xff. Hence, we can safely ignore them.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/hid/hid-wiimote-core.c b/drivers/hid/hid-wiimote-core.c
index ea00030defd6..e0ac84b2f74b 100644
--- a/drivers/hid/hid-wiimote-core.c
+++ b/drivers/hid/hid-wiimote-core.c
@@ -1276,11 +1276,19 @@ static bool valid_ext_handler(const struct wiimod_ops *ops, size_t len)
 static void handler_ext(struct wiimote_data *wdata, const __u8 *payload,
                         size_t len)
 {
+        static const __u8 invalid[21] = { 0xff, 0xff, 0xff, 0xff,
+                                          0xff, 0xff, 0xff, 0xff,
+                                          0xff, 0xff, 0xff, 0xff,
+                                          0xff, 0xff, 0xff, 0xff,
+                                          0xff, 0xff, 0xff, 0xff,
+                                          0xff };
         const __u8 *iter, *mods;
         const struct wiimod_ops *ops;
         bool is_mp;
 
-        if (len < 6)
+        if (len > 21)
+                len = 21;
+        if (len < 6 || !memcmp(payload, invalid, len))
                 return;
 
         /* if MP is active, track MP slot hotplugging */