batman-adv: Improve exception handling in batadv_throw_uevent()

The kfree() function was called in up to three cases by
the batadv_throw_uevent() function during error handling
even if the passed variable contained a null pointer.
This issue was detected by using the Coccinelle software.

* Thus adjust jump targets.

* Reorder kfree() calls at the end.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

net/batman-adv/main.c

@@ -691,29 +691,31 @@ int batadv_throw_uevent(struct batadv_priv *bat_priv, enum batadv_uev_type type,
 				  "%s%s", BATADV_UEV_TYPE_VAR,
 				  batadv_uev_type_str[type]);
 	if (!uevent_env[0])
-		goto out;
+		goto report_error;
 
 	uevent_env[1] = kasprintf(GFP_ATOMIC,
 				  "%s%s", BATADV_UEV_ACTION_VAR,
 				  batadv_uev_action_str[action]);
 	if (!uevent_env[1])
-		goto out;
+		goto free_first_env;
 
 	/* If the event is DEL, ignore the data field */
 	if (action != BATADV_UEV_DEL) {
 		uevent_env[2] = kasprintf(GFP_ATOMIC,
 					  "%s%s", BATADV_UEV_DATA_VAR, data);
 		if (!uevent_env[2])
-			goto out;
+			goto free_second_env;
 	}
 
 	ret = kobject_uevent_env(bat_kobj, KOBJ_CHANGE, uevent_env);
-out:
-	kfree(uevent_env[0]);
-	kfree(uevent_env[1]);
 	kfree(uevent_env[2]);
+free_second_env:
+	kfree(uevent_env[1]);
+free_first_env:
+	kfree(uevent_env[0]);
 
 	if (ret)
+report_error:
 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 			   "Impossible to send uevent for (%s,%s,%s) event (err: %d)\n",
 			   batadv_uev_type_str[type],