[PATCH] netrom: fix info leak via msg_name in nr_recvmsg()

[Luis Henriques]

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