[Lucid CVE-2013-3229] iucv: Fix missing msg_namelen update in iucv_sock_recvmsg()

[Luis Henriques]

On Mon, May 20, 2013 at 01:06:28PM +0100, Luis Henriques wrote:
> From: Mathias Krause <minipli at googlemail.com>
> 
> CVE-2013-3229
> 
> BugLink: https://bugs.launchpad.net/bugs/1172381
> 
> The current code does not fill the msg_name member in case it is set.
> It also does not set the msg_namelen member to 0 and therefore makes
> net/socket.c leak the local, uninitialized sockaddr_storage variable
> to userland -- 128 bytes of kernel stack memory.
> 
> Fix that by simply setting msg_namelen to 0 as obviously nobody cared
> about iucv_sock_recvmsg() not filling the msg_name in case it was set.
> 
> Cc: Ursula Braun <ursula.braun at de.ibm.com>
> Signed-off-by: Mathias Krause <minipli at googlemail.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (back ported from commit a5598bd9c087dc0efc250a5221e5d0e6f584ee88)
> 
> Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
> ---
>  net/iucv/af_iucv.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
> index bada1b9..f605b23 100644
> --- a/net/iucv/af_iucv.c
> +++ b/net/iucv/af_iucv.c
> @@ -1160,6 +1160,8 @@ static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
>  	struct sk_buff *skb, *rskb, *cskb;
>  	int err = 0;
>  
> +	msg->msg_namelen = 0;
> +
>  	if ((sk->sk_state == IUCV_DISCONN || sk->sk_state == IUCV_SEVERED) &&
>  	    skb_queue_empty(&iucv->backlog_skb_q) &&
>  	    skb_queue_empty(&sk->sk_receive_queue) &&
> -- 
> 1.8.1.2
> 
> 
> -- 
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Cheers,
--
Luis