Input: cleanse capabilities bits before registering device

To avoid showing garbage in capability bits, zero out bitmasks absent
from dev->evbit in case driver inadvertently leaves some garbage there.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/input/input.c b/drivers/input/input.c
index 910d7be06eff..a31394c1eca8 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1497,6 +1497,25 @@ void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int
 }
 EXPORT_SYMBOL(input_set_capability);
 
+#define INPUT_CLEANSE_BITMASK(dev, type, bits)                          \
+        do {                                                            \
+                if (!test_bit(EV_##type, dev->evbit))                   \
+                        memset(dev->bits##bit, 0,                       \
+                                sizeof(dev->bits##bit));                \
+        } while (0)
+
+static void input_cleanse_bitmasks(struct input_dev *dev)
+{
+        INPUT_CLEANSE_BITMASK(dev, KEY, key);
+        INPUT_CLEANSE_BITMASK(dev, REL, rel);
+        INPUT_CLEANSE_BITMASK(dev, ABS, abs);
+        INPUT_CLEANSE_BITMASK(dev, MSC, msc);
+        INPUT_CLEANSE_BITMASK(dev, LED, led);
+        INPUT_CLEANSE_BITMASK(dev, SND, snd);
+        INPUT_CLEANSE_BITMASK(dev, FF, ff);
+        INPUT_CLEANSE_BITMASK(dev, SW, sw);
+}
+
 /**
  * input_register_device - register device with input core
  * @dev: device to be registered
@@ -1522,6 +1541,9 @@ int input_register_device(struct input_dev *dev)
         /* KEY_RESERVED is not supposed to be transmitted to userspace. */
         __clear_bit(KEY_RESERVED, dev->keybit);
 
+        /* Make sure that bitmasks not mentioned in dev->evbit are clean. */
+        input_cleanse_bitmasks(dev);
+
         /*
          * If delay and period are pre-set by the driver, then autorepeating
          * is handled by the driver itself and we don't do it in input.c.