iucv: Fix missing msg_namelen update in iucv_sock_recvmsg()

[ Upstream commit a5598bd9c087dc0efc250a5221e5d0e6f584ee88 ]

The current code does not fill the msg_name member in case it is set.
It also does not set the msg_namelen member to 0 and therefore makes
net/socket.c leak the local, uninitialized sockaddr_storage variable
to userland -- 128 bytes of kernel stack memory.

Fix that by simply setting msg_namelen to 0 as obviously nobody cared
about iucv_sock_recvmsg() not filling the msg_name in case it was set.

Cc: Ursula Braun <ursula.braun@de.ibm.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/iucv/af_iucv.c b/net/iucv/af_iucv.c
index cf98d625d9585857fc0387200bb69cf380760f82..e836140c75fbf76452ed0f11881f95bf8aef2e67 100644 (file)
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -1356,6 +1356,8 @@ static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
        int blen;
        int err = 0;
 
+       msg->msg_namelen = 0;
+
        if ((sk->sk_state == IUCV_DISCONN || sk->sk_state == IUCV_SEVERED) &&
            skb_queue_empty(&iucv->backlog_skb_q) &&
            skb_queue_empty(&sk->sk_receive_queue) &&