netdev - Re: [PATCH] net: mdiobus: Fix memory leak in __mdiobus

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Date:   Tue, 28 Sep 2021 13:39:08 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Pavel Skripkin <paskripkin@...il.com>
Cc:     Yanfei Xu <yanfei.xu@...driver.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        andrew@...n.ch, hkallweit1@...il.com, linux@...linux.org.uk,
        davem@...emloft.net, kuba@...nel.org, p.zabel@...gutronix.de,
        syzbot+398e7dc692ddbbb4cfec@...kaller.appspotmail.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Dongliang Mu <mudongliangabcd@...il.com>
Subject: Re: [PATCH] net: mdiobus: Fix memory leak in __mdiobus_register

No, the syzbot link was correct.

You gave me that link again but I think you must be complaining about
a different bug which involves mdiobus_free().  Your bug is something
like this:

drivers/staging/netlogic/xlr_net.c
   838          err = mdiobus_register(priv->mii_bus);
   839          if (err) {
   840                  mdiobus_free(priv->mii_bus);

This error path will leak.

   841                  pr_err("mdio bus registration failed\n");
   842                  return err;
   843          }

Your patch is more complicated than necessary...  Just do:

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index ee8313a4ac71..c380a30a77bc 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -538,6 +538,7 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 	bus->dev.groups = NULL;
 	dev_set_name(&bus->dev, "%s", bus->id);
 
+	bus->state = MDIOBUS_UNREGISTERED;
 	err = device_register(&bus->dev);
 	if (err) {
 		pr_err("mii_bus %s failed to register\n", bus->id);


regards,
dan carpenter