iucv: Fix missing msg_namelen update in iucv_sock_recvmsg()

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>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index a7d11ffe4284..bf6935820001 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -1328,6 +1328,8 @@ static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
         struct sk_buff *skb, *rskb, *cskb;
         int err = 0;
 
+        msg->msg_namelen = 0;
+
         if ((sk->sk_state == IUCV_DISCONN) &&
             skb_queue_empty(&iucv->backlog_skb_q) &&
             skb_queue_empty(&sk->sk_receive_queue) &&