Q: Given the following code slice:
```
1 int
2 main (int argc, char **argv)
4   int limit;
6   char *sieve;
7   size_t size, i;
12   if (argc != 2)
18   limit = atoi (argv[1]);
19   if (limit < 3)
23   if ( !(limit & 1))
24     limit--;
26   size = (limit-1)/2;
28   sieve = xalloc (size);
29   memset (sieve, 1, size);
34   for (i = 0; i < size;)
36       unsigned p = 3+2*i;
37       unsigned j;
41       for (j = (p*p - 3)/2; j < size; j+= p)
42         sieve[j] = 0;
44       while (i < size && sieve[++i] == 0)```
which has a CWE-125 vulnerability at line:
```
44       while (i < size && sieve[++i] == 0)
```
Please analyze the root cause of the vulnerability.