confile: error out if a network configuration key has no subkey

src/lxc/confile.c

@@ -3628,6 +3628,10 @@ static struct lxc_config_t *get_network_config_ops(const char *key,
 	/* lxc.net.<idx>.<subkey> */
 	if (idx_end) {
 		*idx_end = '.';
+		if (strlen(idx_end + 1) == 0) {
+			ERROR("No subkey in network configuration key \"%s\"", key);
+			goto on_error;
+		}
 
 		memmove(copy + 8, idx_end + 1, strlen(idx_end + 1));
 		copy[strlen(key) - numstrlen + 1] = '\0';

src/lxc/confile_legacy.c

@@ -90,6 +90,10 @@ int set_config_network_legacy_nic(const char *key, const char *value,
 	if (!p)
 		goto out;
 
+	if (strlen(p + 1) == 0) {
+	    ERROR("No subkey in network configuration key \"%s\"", key);
+	    goto out;
+	}
 	strcpy(copy + 12, p + 1);
 	config = lxc_get_config(copy);
 	if (!config) {

src/tests/parse_config_file.c

@@ -166,6 +166,16 @@ static int set_invalid_netdev(struct lxc_container *c) {
 		return -1;
 	}
 
+	if (c->set_config_item(c, "lxc.net.0.", "veth")) {
+		lxc_error("%s\n", "lxc.net.0. should be invalid");
+		return -1;
+	}
+
+	if (c->set_config_item(c, "lxc.network.0.", "veth")) {
+		lxc_error("%s\n", "lxc.network.0. should be invalid");
+		return -1;
+	}
+
 	c->clear_config(c);
 	c->lxc_conf = NULL;