Bluetooth: fix possible info leak in bt_sock_recvmsg()

[ 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@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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
index 062124cd89cf2a560cff39b80b7f3cbcdb66c1a3..838f113bfdd9be00912777d6e656c7536ba8acfd 100644 (file)
--- a/net/bluetooth/af_bluetooth.c
+++ b/net/bluetooth/af_bluetooth.c
@@ -245,6 +245,8 @@ int bt_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
        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, struct socket *sock,
                return err;
        }
 
-       msg->msg_namelen = 0;
-
        copied = skb->len;
        if (len < copied) {
                msg->msg_flags |= MSG_TRUNC;