wifi: nl80211: don't free NULL coalescing rule

If the parsing fails, we can dereference a NULL pointer here.

Cc: stable@vger.kernel.org
Fixes: be29b99a ("cfg80211/nl80211: Add packet coalesce support")
Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240418105220.b328f80406e7.Id75d961050deb05b3e4e354e024866f350c68103@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -14030,6 +14030,8 @@ static int nl80211_set_coalesce(struct sk_buff *skb, struct genl_info *info)
 error:
 	for (i = 0; i < new_coalesce.n_rules; i++) {
 		tmp_rule = &new_coalesce.rules[i];
+		if (!tmp_rule)
+			continue;
 		for (j = 0; j < tmp_rule->n_patterns; j++)
 			kfree(tmp_rule->patterns[j].mask);
 		kfree(tmp_rule->patterns);