Q: Given the following code slice:
```
1 int
2 main(int argc, char* argv[])
5 	int c;
8 	extern char *optarg;
11 	while ((c = getopt(argc, argv, "c:h:r:v:z")) != -1)
12 		switch (c) {
28 			horizSubSampling = atoi(optarg);```
which has a CWE-190 vulnerability at line:
```
28 			horizSubSampling = atoi(optarg);
```
Please analyze the root cause of the vulnerability.