Bluetooth: fix possible info leak in bt_sock_recvmsg()

commit 4683f42fde3977bdb4e8a09622788cc8b5313778 upstream.

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@holtmann.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
index 404a8500fd031b254b0049a6c97b8ff6f7805675..0891857b7ca22d159a86d5f016dcfcfa812e4541 100644 (file)
--- a/net/bluetooth/af_bluetooth.c
+++ b/net/bluetooth/af_bluetooth.c
@@ -240,14 +240,14 @@ int bt_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
        if (flags & (MSG_OOB))
                return -EOPNOTSUPP;
 
+       msg->msg_namelen = 0;
+
        if (!(skb = skb_recv_datagram(sk, flags, noblock, &err))) {
                if (sk->sk_shutdown & RCV_SHUTDOWN)
                        return 0;
                return err;
        }
 
-       msg->msg_namelen = 0;
-
        copied = skb->len;
        if (len < copied) {
                msg->msg_flags |= MSG_TRUNC;