Q: Given the following code slice:
```
1 ice_debugfs_module_write(struct file *filp, const char __user *buf,
2 			 size_t count, loff_t *ppos)
7 	char user_val[16], *cmd_buf;
11 	if (*ppos != 0 || count > 8)
14 	cmd_buf = memdup_user(buf, count);```
which has a CWE-125 vulnerability at line:
```
14 	cmd_buf = memdup_user(buf, count);
```
Please analyze the root cause of the vulnerability.