Input: add bounds checking to input_set_capability()

Update input_set_capability() to prevent kernel panic in case the
event code exceeds the bitmap for the given event type.

Suggested-by: Tomasz Moń <tomasz.mon@camlingroup.com>
Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Reviewed-by: Tomasz Moń <tomasz.mon@camlingroup.com>
Link: https://lore.kernel.org/r/20220320032537.545250-1-jeff@labundy.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/input.c b/drivers/input/input.c
index 7c7e404..6428cda 100644 (file)
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -47,6 +47,17 @@ static DEFINE_MUTEX(input_mutex);
 
 static const struct input_value input_value_sync = { EV_SYN, SYN_REPORT, 1 };
 
+static const unsigned int input_max_code[EV_CNT] = {
+       [EV_KEY] = KEY_MAX,
+       [EV_REL] = REL_MAX,
+       [EV_ABS] = ABS_MAX,
+       [EV_MSC] = MSC_MAX,
+       [EV_SW] = SW_MAX,
+       [EV_LED] = LED_MAX,
+       [EV_SND] = SND_MAX,
+       [EV_FF] = FF_MAX,
+};
+
 static inline int is_event_supported(unsigned int code,
                                     unsigned long *bm, unsigned int max)
 {
@@ -2110,6 +2121,14 @@ EXPORT_SYMBOL(input_get_timestamp);
  */
 void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int code)
 {
+       if (type < EV_CNT && input_max_code[type] &&
+           code > input_max_code[type]) {
+               pr_err("%s: invalid code %u for type %u\n", __func__, code,
+                      type);
+               dump_stack();
+               return;
+       }
+
        switch (type) {
        case EV_KEY:
                __set_bit(code, dev->keybit);