netdev - [PATCH 11/16] netrom: fix info leak via msg_name in nr

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Date:	Sun,  7 Apr 2013 13:51:57 +0200
From:	Mathias Krause <minipli@...glemail.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org,
	Allan Stephens <allan.stephens@...driver.com>,
	Aloisio Almeida Jr <aloisio.almeida@...nbossa.org>,
	Andy King <acking@...are.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Dmitry Torokhov <dtor@...are.com>,
	George Zhang <georgezhang@...are.com>,
	Gustavo Padovan <gustavo@...ovan.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	Jon Maloy <jon.maloy@...csson.com>,
	Lauro Ramos Venancio <lauro.venancio@...nbossa.org>,
	Marcel Holtmann <marcel@...tmann.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Samuel Ortiz <samuel@...tiz.org>,
	Sjur Braendeland <sjur.brandeland@...ricsson.com>,
	Ursula Braun <ursula.braun@...ibm.com>,
	Brad Spengler <spender@...ecurity.net>,
	Mathias Krause <minipli@...glemail.com>
Subject: [PATCH 11/16] netrom: fix info leak via msg_name in nr_recvmsg()

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@...ux-mips.org>
Signed-off-by: Mathias Krause <minipli@...glemail.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 d1fa1d9..7fcb307 100644
--- a/net/netrom/af_netrom.c
+++ b/net/netrom/af_netrom.c
@@ -1173,6 +1173,7 @@ static int nr_recvmsg(struct kiocb *iocb, struct socket *sock,
 	}
 
 	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);
-- 
1.7.10.4

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