Subject: Re: [PATCH] Fix pppol2tp getsockname()

From: James Chapman <[email-masked]>
Date: Tue, 20 Mar 2012 11:49:57 +0000

On 19/03/12 03:15, Benjamin LaHaise wrote:
> 
> While testing L2TP functionality, I came across a bug in getsockname().  The
> IP address returned within the pppol2tp_addr's addr memember was not being
> set to the IP address in use.  This bug is caused by using inet_sk() on the
> wrong socket (the L2TP socket rather than the underlying UDP socket), and was
> likely introduced during the addition of L2TPv3 support.
> ---
>  net/l2tp/l2tp_ppp.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
> index 96bc7a6..9b07191 100644
> --- a/net/l2tp/l2tp_ppp.c
> +++ b/net/l2tp/l2tp_ppp.c
> @@ -915,7 +915,7 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
>  		goto end_put_sess;
>  	}
>  
> -	inet = inet_sk(sk);
> +	inet = inet_sk(tunnel->sock);
>  	if (tunnel->version == 2) {
>  		struct sockaddr_pppol2tp sp;
>  		len = sizeof(sp);

The patch is incorrect.

This is supposed to return the socket info of the pppol2tp socket, not
the tunnel socket. It is used by pppd's pppol2tp plugin to check that
the fd supplied is the right socket type.

-- 
James Chapman
Katalix Systems Ltd
http://www.katalix.com
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