netdev - [PATCH 14/16] tipc: fix info leaks via msg_name in recv_msg/recv

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Date:	Sun,  7 Apr 2013 13:52:00 +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 14/16] tipc: fix info leaks via msg_name in recv_msg/recv_stream

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@...csson.com>
Cc: Allan Stephens <allan.stephens@...driver.com>
Signed-off-by: Mathias Krause <minipli@...glemail.com>
---
 net/tipc/socket.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index a9622b6..515ce38 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -790,6 +790,7 @@ 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 */
@@ -904,6 +905,9 @@ 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;
+
 	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 restart:
 
@@ -1013,6 +1017,9 @@ 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;
+
 	target = sock_rcvlowat(sk, flags & MSG_WAITALL, buf_len);
 	timeout = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 
-- 
1.7.10.4

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