linux-kernel - [100/118] Bluetooth: fix possible info leak in bt_sock

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Message-ID: <lsq.1368193181.914423718@decadent.org.uk>
Date:	Fri, 10 May 2013 14:39:41 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Marcel Holtmann" <marcel@...tmann.org>,
	"David S. Miller" <davem@...emloft.net>,
	"Johan Hedberg" <johan.hedberg@...il.com>,
	"Mathias Krause" <minipli@...glemail.com>,
	"Gustavo Padovan" <gustavo@...ovan.org>
Subject: [100/118] Bluetooth: fix possible info leak in bt_sock_recvmsg()

3.2.45-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Mathias Krause <minipli@...glemail.com>

[ Upstream commit 4683f42fde3977bdb4e8a09622788cc8b5313778 ]

In case the socket is already shutting down, bt_sock_recvmsg() returns
with 0 without updating msg_namelen leading to net/socket.c leaking the
local, uninitialized sockaddr_storage variable to userland -- 128 bytes
of kernel stack memory.

Fix this by moving the msg_namelen assignment in front of the shutdown
test.

Cc: Marcel Holtmann <marcel@...tmann.org>
Cc: Gustavo Padovan <gustavo@...ovan.org>
Cc: Johan Hedberg <johan.hedberg@...il.com>
Signed-off-by: Mathias Krause <minipli@...glemail.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/bluetooth/af_bluetooth.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/bluetooth/af_bluetooth.c
+++ b/net/bluetooth/af_bluetooth.c
@@ -245,6 +245,8 @@ int bt_sock_recvmsg(struct kiocb *iocb,
 	if (flags & (MSG_OOB))
 		return -EOPNOTSUPP;
 
+	msg->msg_namelen = 0;
+
 	skb = skb_recv_datagram(sk, flags, noblock, &err);
 	if (!skb) {
 		if (sk->sk_shutdown & RCV_SHUTDOWN)
@@ -252,8 +254,6 @@ int bt_sock_recvmsg(struct kiocb *iocb,
 		return err;
 	}
 
-	msg->msg_namelen = 0;
-
 	copied = skb->len;
 	if (len < copied) {
 		msg->msg_flags |= MSG_TRUNC;

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