Q: Given the following code slice:
```
1 static ssize_t rvu_dbg_qsize_write(struct file *filp,
2 				   const char __user *buffer, size_t count,
7 	char *cmd_buf, *cmd_buf_tmp, *subtoken;
14 	cmd_buf = memdup_user(buffer, count + 1);```
which has a CWE-125 vulnerability at line:
```
14 	cmd_buf = memdup_user(buffer, count + 1);
```
Please analyze the root cause of the vulnerability.