iwlwifi: mvm: check sta_id/drain values in debugfs

commit 60765a47 upstream.

The station ID must be valid, if it's out of range then
the array access may crash. Validate the station ID to
the array length, and also validate the drain value even
if that doesn't matter all that much.

Fixes: 8ca151b5 ("iwlwifi: add the MVM driver")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/wireless/iwlwifi/mvm/debugfs.c

@@ -119,6 +119,10 @@ static ssize_t iwl_dbgfs_sta_drain_write(struct file *file,
 
 	if (sscanf(buf, "%d %d", &sta_id, &drain) != 2)
 		return -EINVAL;
+	if (sta_id < 0 || sta_id >= IWL_MVM_STATION_COUNT)
+		return -EINVAL;
+	if (drain < 0 || drain > 1)
+		return -EINVAL;
 
 	mutex_lock(&mvm->mutex);