diff --git a/drivers/misc/ibmasm/ibmasmfs.c b/drivers/misc/ibmasm/ibmasmfs.c
index f68a8957b98f..dfdfa9ba4747 100644
--- a/drivers/misc/ibmasm/ibmasmfs.c
+++ b/drivers/misc/ibmasm/ibmasmfs.c
@@ -303,6 +303,8 @@ static ssize_t command_file_write(struct file *file, const char __user *ubuff, s
 		return -EINVAL;
 	if (count == 0 || count > IBMASM_CMD_MAX_BUFFER_SIZE)
 		return 0;
+	if (count < sizeof(struct dot_command_header))
+		return -EINVAL;
 	if (*offset != 0)
 		return 0;
 
@@ -319,6 +321,11 @@ static ssize_t command_file_write(struct file *file, const char __user *ubuff, s
 		return -EFAULT;
 	}
 
+	if (count < get_dot_command_size(cmd->buffer)) {
+		command_put(cmd);
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&command_data->sp->lock, flags);
 	if (command_data->command) {
 		spin_unlock_irqrestore(&command_data->sp->lock, flags);