Re: [PATCH v2] nbd: Fix memory leak in nbd_add_socket

[Markus Elfring <Markus.Elfring@web.de>]

> If we add first socket to nbd, config->socks is malloced but
> num_connections does not update(nsock's allocation fail), the memory
> is leaked. Cause in later nbd_config_put(), will only free config->socks
> when num_connections is not 0.
>
> Let nsock's allocation first to avoid this.

I suggest to improve this change description.
Can an other wording variant be nicer?


…
> +++ b/drivers/block/nbd.c
> @@ -1037,21 +1037,22 @@  static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
>  		return -EBUSY;
>  	}
>
> +	nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);

Please use the following code variant.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=4333a9b0b67bb4e8bcd91bdd80da80b0ec151162#n854

+	nsock = kzalloc(sizeof(*nsock), GFP_KERNEL);


…
>  	if (!socks) {
>  		sockfd_put(sock);
> +		kfree(nsock);
>  		return -ENOMEM;
>  	}

Please take another software design possibility into account.

 	if (!socks) {
-		sockfd_put(sock);
-		return -ENOMEM;
+		kfree(nsock);
+		goto put_socket;
 	}


Regards,
Markus