Re: [ 184/184] tipc: fix info leaks via msg_name in

[Ben Hutchings]

On Tue, 2013-06-04 at 19:24 +0200, Willy Tarreau wrote:
> 2.6.32-longterm review patch.  If anyone has any objections, please let me know.
> 
> ------------------
>  recv_msg/recv_stream
> 
> From: Mathias Krause <minipli@xxxxxxxxxxxxxx>

commit 60085c3d009b0df252547adb336d1ccca5ce52ec upstream.

> The code in set_orig_addr() does not initialize all of the members of
> struct sockaddr_tipc when filling the sockaddr info -- namely the union
> is only partly filled. This will make recv_msg() and recv_stream() --
> the only users of this function -- leak kernel stack memory as the
> msg_name member is a local variable in net/socket.c.
> 
> Additionally to that both recv_msg() and recv_stream() fail to update
> the msg_namelen member to 0 while otherwise returning with 0, i.e.
> "success". This is the case for, e.g., non-blocking sockets. This will
> lead to a 128 byte kernel stack leak in net/socket.c.
> 
> Fix the first issue by initializing the memory of the union with
> memset(0). Fix the second one by setting msg_namelen to 0 early as it
> will be updated later if we're going to fill the msg_name member.
> 
> Cc: Jon Maloy <jon.maloy@xxxxxxxxxxxx>
> Cc: Allan Stephens <allan.stephens@xxxxxxxxxxxxx>
> Signed-off-by: Mathias Krause <minipli@xxxxxxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> [dannf: backported to Debian's 2.6.32]
> Signed-off-by: Willy Tarreau <w@xxxxxx>
> ---
>  net/tipc/socket.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/net/tipc/socket.c b/net/tipc/socket.c
> index 8ebf4975..eccb86b 100644
> --- a/net/tipc/socket.c
> +++ b/net/tipc/socket.c
> @@ -800,6 +800,7 @@ static void set_orig_addr(struct msghdr *m, struct tipc_msg *msg)
>  	if (addr) {
>  		addr->family = AF_TIPC;
>  		addr->addrtype = TIPC_ADDR_ID;
> +		memset(&addr->addr, 0, sizeof(addr->addr));
>  		addr->addr.id.ref = msg_origport(msg);
>  		addr->addr.id.node = msg_orignode(msg);
>  		addr->addr.name.domain = 0;   	/* could leave uninitialized */
> @@ -916,6 +917,9 @@ static int recv_msg(struct kiocb *iocb, struct socket *sock,
>  		goto exit;
>  	}
>  
> +	/* will be updated in set_orig_addr() if needed */
> +	m->msg_namelen = 0;
> +
>  restart:
>  
>  	/* Look for a message in receive queue; wait if necessary */
> @@ -1049,6 +1053,9 @@ static int recv_stream(struct kiocb *iocb, struct socket *sock,
>  		goto exit;
>  	}
>  
> +	/* will be updated in set_orig_addr() if needed */
> +	m->msg_namelen = 0;
> +
>  restart:
>  
>  	/* Look for a message in receive queue; wait if necessary */

-- 
Ben Hutchings
Theory and practice are closer in theory than in practice.
                                - John Levine, moderator of comp.compilers

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