Q: Given the following code slice:
```
1 static int nl80211_set_coalesce(struct sk_buff *skb, struct genl_info *info)
3 	struct cfg80211_registered_device *rdev = info->user_ptr[0];
4 	const struct wiphy_coalesce_support *coalesce = rdev->wiphy.coalesce;
6 	struct cfg80211_coalesce *n_coalesce;
7 	int err, rem_rule, n_rules = 0, i, j;
8 	struct nlattr *rule;
9 	struct cfg80211_coalesce_rules *tmp_rule;
11 	if (!rdev->wiphy.coalesce || !rdev->ops->set_coalesce)
14 	if (!info->attrs[NL80211_ATTR_COALESCE_RULE]) {
22 		n_rules++;
23 	if (n_rules > coalesce->n_rules)
26 	new_coalesce.rules = kcalloc(n_rules, sizeof(new_coalesce.rules[0]),
28 	if (!new_coalesce.rules)
31 	new_coalesce.n_rules = n_rules;
32 	i = 0;
36 		err = nl80211_parse_coalesce_rule(rdev, rule,
38 		if (err)
41 		i++;
44 	err = rdev_set_coalesce(rdev, &new_coalesce);
45 	if (err)
48 	n_coalesce = kmemdup(&new_coalesce, sizeof(new_coalesce), GFP_KERNEL);
49 	if (!n_coalesce) {
58 	for (i = 0; i < new_coalesce.n_rules; i++) {
59 		tmp_rule = &new_coalesce.rules[i];```
which has a CWE-476 vulnerability at line:
```
59 		tmp_rule = &new_coalesce.rules[i];
```
Please analyze the root cause of the vulnerability.