netdev - Re: [PATCH v3 net] ipv4: fix error path in fou

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Date:   Sun, 8 Aug 2021 14:05:31 -0600
From:   David Ahern <dsahern@...il.com>
To:     Kangmin Park <l4stpr0gr4m@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 net] ipv4: fix error path in fou_create()

On 8/8/21 1:05 AM, Kangmin Park wrote:
> sock is always NULL when udp_sock_create() is failed and fou is
> always NULL when kzalloc() is failed in error label.
> 
> So, add error_sock and error_alloc label and fix the error path
> in those cases.
> 
> Signed-off-by: Kangmin Park <l4stpr0gr4m@...il.com>
> ---
> v3:
>  - change commit message
>  - fix error path
> ---
>  net/ipv4/fou.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
> index e5f69b0bf3df..f1d99e776bb8 100644
> --- a/net/ipv4/fou.c
> +++ b/net/ipv4/fou.c
> @@ -572,13 +572,13 @@ static int fou_create(struct net *net, struct fou_cfg *cfg,
>  	/* Open UDP socket */
>  	err = udp_sock_create(net, &cfg->udp_config, &sock);
>  	if (err < 0)
> -		goto error;
> +		goto error_sock;
>  
>  	/* Allocate FOU port structure */
>  	fou = kzalloc(sizeof(*fou), GFP_KERNEL);
>  	if (!fou) {
>  		err = -ENOMEM;
> -		goto error;
> +		goto error_alloc;
>  	}
>  
>  	sk = sock->sk;
> @@ -627,9 +627,10 @@ static int fou_create(struct net *net, struct fou_cfg *cfg,
>  
>  error:
>  	kfree(fou);
> +error_alloc:
>  	if (sock)
>  		udp_tunnel_sock_release(sock);
> -
> +error_sock:
>  	return err;
>  }
>  
> 

since sock and fou are initialized to NULL, kfree(NULL) is allowed and
there is an 'if (sock)' check before the release, no fix is really needed.