[Lucid CVE-2013-3232] netrom: fix info leak via msg_name in nr_recvmsg()

[Luis Henriques]

On Mon, May 20, 2013 at 01:06:49PM +0100, Luis Henriques wrote:
> From: Mathias Krause <minipli at googlemail.com>
> 
> CVE-2013-3232
> 
> BugLink: https://bugs.launchpad.net/bugs/1172386
> 
> In case msg_name is set the sockaddr info gets filled out, as
> requested, but the code fails to initialize the padding bytes of
> struct sockaddr_ax25 inserted by the compiler for alignment. Also
> the sax25_ndigis member does not get assigned, leaking four more
> bytes.
> 
> Both issues lead to the fact that the code will leak uninitialized
> kernel stack bytes in net/socket.c.
> 
> Fix both issues by initializing the memory with memset(0).
> 
> Cc: Ralf Baechle <ralf at linux-mips.org>
> Signed-off-by: Mathias Krause <minipli at googlemail.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (cherry picked from commit 3ce5efad47b62c57a4f5c54248347085a750ce0e)
> 
> Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
> ---
>  net/netrom/af_netrom.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
> index 7a83495..d240523 100644
> --- a/net/netrom/af_netrom.c
> +++ b/net/netrom/af_netrom.c
> @@ -1181,6 +1181,7 @@ static int nr_recvmsg(struct kiocb *iocb, struct socket *sock,
>  	skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
>  
>  	if (sax != NULL) {
> +		memset(sax, 0, sizeof(sax));
>  		sax->sax25_family = AF_NETROM;
>  		skb_copy_from_linear_data_offset(skb, 7, sax->sax25_call.ax25_call,
>  			      AX25_ADDR_LEN);
> -- 
> 1.8.1.2
> 
> 
> -- 
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Cheers,
--
Luis